"This is another example of the growing levels of extremism in Gaza and further evidence, if that were needed, of the urgency to change the circumstances on the ground," UNRWA Gaza director John Ging said.
UN spokesman Adnan Abu Hasna said the attackers tied up the guards at the camp in central Gaza before setting fire to chairs, tables, easels and other equipment.
UNRWA vowed to repair the camp and said it would continue to maintain its 1,200 summer camps, in which over 250,000 Gaza children participate in sports, swimming, arts and theatre during the summer break.
The Hamas-run interior ministry condemned the attack and blamed it on "groups led by those with misguided ideas who want to distort the situation in Gaza."
It said it had opened an investigation and offered to provide extra security at the camps.
Hamas had also condemned the previous attack on May 23, in which dozens of masked gunmen had tied up a night watchman, burned down tents and left a threatening letter addressed to Ging.
Hamas has taken only limited steps to impose Islamic values on Gaza's already conservative society since it seized power in June 2007, routing the secular Fatah movement that dominates the Western-backed Palestinian Authority.
The Islamist group operates its own network of summer camps that separate boys and girls and focus on teaching the Koran.
In recent years more radical groups have carried out several bombings and other attacks targeting Christian organisations, beauty parlors and cafes catering to men and women, rarely wounding anyone.
UNRWA provides vital food aid and runs schools and clinics for Gaza's more than one million registered refugees, two-thirds of the territory's population.
Most of Gaza's refugees are the descendants of the hundreds of thousands of Palestinians who were driven out or fled from what is now Israel during the 1948 war that attended the creation of the Jewish state.
----------------------------------------------------------------------------
UN spokesman Adnan Abu Hasna said the attackers tied up the guards at the camp in central Gaza before setting fire to chairs, tables, easels and other equipment.
UNRWA vowed to repair the camp and said it would continue to maintain its 1,200 summer camps, in which over 250,000 Gaza children participate in sports, swimming, arts and theatre during the summer break.
The Hamas-run interior ministry condemned the attack and blamed it on "groups led by those with misguided ideas who want to distort the situation in Gaza."
It said it had opened an investigation and offered to provide extra security at the camps.
Hamas had also condemned the previous attack on May 23, in which dozens of masked gunmen had tied up a night watchman, burned down tents and left a threatening letter addressed to Ging.
Hamas has taken only limited steps to impose Islamic values on Gaza's already conservative society since it seized power in June 2007, routing the secular Fatah movement that dominates the Western-backed Palestinian Authority.
The Islamist group operates its own network of summer camps that separate boys and girls and focus on teaching the Koran.
In recent years more radical groups have carried out several bombings and other attacks targeting Christian organisations, beauty parlors and cafes catering to men and women, rarely wounding anyone.
UNRWA provides vital food aid and runs schools and clinics for Gaza's more than one million registered refugees, two-thirds of the territory's population.
Most of Gaza's refugees are the descendants of the hundreds of thousands of Palestinians who were driven out or fled from what is now Israel during the 1948 war that attended the creation of the Jewish state.
----------------------------------------------------------------------------