"I urge Uighur and Han civic leaders and the Chinese authorities at all levels, to exercise great restraint so as not to spark further violence and loss of life," said Navi Pillay in a statement.
Offering her condolences to families of the victims, Pillay described the event as a "major tragedy" and said the toll was an "extraordinarily high number of people to be killed and injured in less than a day of rioting."
The United States said late Monday it was "deeply concerned" and called for restraint.
"We are deeply concerned over reports of many deaths and injuries from violence in Urumqi in western China," White House spokesman Robert Gibbs said in a statement issued in Moscow, where US President Barack Obama was on an official visit.
"We call on all in Xinjiang to exercise restraint," Gibbs added.
US House Speaker Nancy Pelosi blamed China's "harsh policies" for fuelling resentment among its Uighur population and urged Beijing to seek a dialogue with the Muslim minority.
"It is long past time for Chinese leaders to pursue activities that further dialogue and understanding with the Uighur people and respect minority rights as guaranteed under Chinese law," she said.
The European Union also called for restraint.
"The EU expresses its strong concern over the unrest," the bloc's Swedish presidency said in a statement. "The EU calls for restraint on all sides and for the situation to be resolved peacefully."
The worst reported ethnic violence in China for decades saw thousands of Muslim Uighurs, who have long harboured resentment to Chinese rule, take to the streets of Xinjiang's capital Urumqi on Sunday in riots that killed scores of people and injured more than 1,080.
Police rounded up more than 1,430 people over the unrest, but violence flared again Tuesday as thousands of angry Han Chinese took to the streets of Urumqi calling for revenge against the Uighurs.
European powers also voiced concern over the deadly clashes Tuesday.
German Chancellor Angela Merkel said she would speak to China's President Hu Jintao about the worsening violence at the Group of Eight summit in Italy which starts Wednesday.
"We will have the opportunity to address these questions with the Chinese president in L'Aquila," Merkel told reporters, referring to the Italian city where leaders are gathering for the G8. "I will use this opportunity."
France expressed concern and said the European Union was discussing how to respond to the violence.
"We are worried and concerned," said French foreign ministry spokesman Eric Chevallier. "There will probably be a European response."
In the Netherlands, the consular section of the Chinese embassy was closed to the public Tuesday, a day after a protest at its doorstep over the unrest.
The embassy announced the closure on its website, after Dutch police arrested 142 people Monday when protesters began hurling rocks and paving stones at the mission.
German police said three Molotov cocktails were thrown at the Chinese consulate in Munich overnight between Sunday and Monday, setting a Chinese flag on fire.
Australian Prime Minister Kevin Rudd added his voice to calls for moderation in conflict riven Xinjiang.
"There has been a large loss of life. There has been a lot of violence and restraint is required now on the part of all parties," the prime minister said after a bilateral meeting with Merkel in Berlin.
The Organisation of the Islamic Conference (OIC) decried Tuesday "the disproportionate use of force" and called on Beijing to investigate "these serious incidents and bring the people responsible to justice swiftly".
An OIC spokesman highlighted Beijing's "friendly relations with the Muslim world in the past" and urged China's leaders to find a solution to the unrest by examining why it had erupted.
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Offering her condolences to families of the victims, Pillay described the event as a "major tragedy" and said the toll was an "extraordinarily high number of people to be killed and injured in less than a day of rioting."
The United States said late Monday it was "deeply concerned" and called for restraint.
"We are deeply concerned over reports of many deaths and injuries from violence in Urumqi in western China," White House spokesman Robert Gibbs said in a statement issued in Moscow, where US President Barack Obama was on an official visit.
"We call on all in Xinjiang to exercise restraint," Gibbs added.
US House Speaker Nancy Pelosi blamed China's "harsh policies" for fuelling resentment among its Uighur population and urged Beijing to seek a dialogue with the Muslim minority.
"It is long past time for Chinese leaders to pursue activities that further dialogue and understanding with the Uighur people and respect minority rights as guaranteed under Chinese law," she said.
The European Union also called for restraint.
"The EU expresses its strong concern over the unrest," the bloc's Swedish presidency said in a statement. "The EU calls for restraint on all sides and for the situation to be resolved peacefully."
The worst reported ethnic violence in China for decades saw thousands of Muslim Uighurs, who have long harboured resentment to Chinese rule, take to the streets of Xinjiang's capital Urumqi on Sunday in riots that killed scores of people and injured more than 1,080.
Police rounded up more than 1,430 people over the unrest, but violence flared again Tuesday as thousands of angry Han Chinese took to the streets of Urumqi calling for revenge against the Uighurs.
European powers also voiced concern over the deadly clashes Tuesday.
German Chancellor Angela Merkel said she would speak to China's President Hu Jintao about the worsening violence at the Group of Eight summit in Italy which starts Wednesday.
"We will have the opportunity to address these questions with the Chinese president in L'Aquila," Merkel told reporters, referring to the Italian city where leaders are gathering for the G8. "I will use this opportunity."
France expressed concern and said the European Union was discussing how to respond to the violence.
"We are worried and concerned," said French foreign ministry spokesman Eric Chevallier. "There will probably be a European response."
In the Netherlands, the consular section of the Chinese embassy was closed to the public Tuesday, a day after a protest at its doorstep over the unrest.
The embassy announced the closure on its website, after Dutch police arrested 142 people Monday when protesters began hurling rocks and paving stones at the mission.
German police said three Molotov cocktails were thrown at the Chinese consulate in Munich overnight between Sunday and Monday, setting a Chinese flag on fire.
Australian Prime Minister Kevin Rudd added his voice to calls for moderation in conflict riven Xinjiang.
"There has been a large loss of life. There has been a lot of violence and restraint is required now on the part of all parties," the prime minister said after a bilateral meeting with Merkel in Berlin.
The Organisation of the Islamic Conference (OIC) decried Tuesday "the disproportionate use of force" and called on Beijing to investigate "these serious incidents and bring the people responsible to justice swiftly".
An OIC spokesman highlighted Beijing's "friendly relations with the Muslim world in the past" and urged China's leaders to find a solution to the unrest by examining why it had erupted.
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