The United Nations expressed concern Tuesday over Hamas authorities' closure of the Sharek Youth Forum, a large independent NGO in Gaza.

"I am very concerned about the recent forced closing of Sharek Youth Forum in Gaza. Sharek is an important NGO partner of the United Nations in its work on behalf of children and the youth in Gaza," said Maxwell Gaylard, the UN humanitarian coordinator in the Palestinian territories.

He noted in a statement that "Sharek’s work forms part of the many important activities carried out by civil society organizations in the occupied Palestinian Territory promoting development and the protection of human rights."

The Gaza attorney general ordered Sharek's branch in Gaza to close last week over a criminal investigation into the group, but officials have not explained the basis for the probe. Sharek officials say they are being targeted for instilling liberal values in Palestinian youths.

Hamas allied police arrested at least 13 people on Sunday at a student-organized demonstration against the closure of the organization. One of the protesters, Mustafa Al-Ghoul, is still in police custody after he refused to sign an agreement not to participate in future protests, members of his family told Ma'an. If he signs the agreement, a relative said, he would also be forced to pay a 5,000 shekel fine and agree to abide by a conservative code of conduct, including refusing contact with women.

The shutdown of the organization and banning of subsequent protests has also drawn condemnation from several Palestinian human rights organizations, including the Palestinian Centre for Human Rights, the Al-Mezan Center for Human Rights, and the Al-Dameer Center for Human Rights.