Palestinian children attending a UNRWA summer camp are trying to set a  number of world records [AFP]

Masked men have attacked and vandalised a UN facility being used to stage summer camps for children in the Gaza Strip, the American Free Press news agency says.

The UN Relief and Works Agency (UNRWA) condemned Thursday's incident, characterising it as "an attack on the children of Gaza as much as on the United Nations".

Chris Gunness, a UNRWA pokesman, said: "The attackers damaged a large billboard, burnt a UN flag and torched part of the stage. None of the UN security personnel at the venue were harmed."

The attack came a day before Palestinian children attending UNRWA camps were to attempt to set a world record for the largest number of children flying kites at one location.

Nevertheless, Gunness said the record attempt would go on as planned and urged local authorities to investigate the incident. Gaza is governed by the Palestinian group Hamas.

The camp was attacked twice before, when masked men with guns set fire to facilities and equipment last year. Those attacks were blamed on religious extremists opposed to boys and girls playing together.

UNRWA's Summer Games programme hosts roughly 250,000 children in the Gaza Strip during six weeks of summer holidays.

Throughout the programme, children have been attempting to set world records - including dribbling footballs and the world's largest handpainting.

On Thursday, 15,000 children were to attempt to break China's record of 10,465 children flying kites.

Source: Agencies