GAZA, Aug 12 (Nidal al-Mughrabi/Reuters) - The United States has suspended operations of the aid organizations it funds in the Hamas-ruled Gaza Strip because the Islamist group had demanded confidential information about their work, a U.S. official told Reuters on Friday.

USAID-funded partner organizations operating in Gaza are forced by Hamas's actions to suspend their assistance work. (They) were put on hold effective August 12, said the official, who is based in the region.

He added that through a series of measures (Hamas) has imposed over the past months, it has created an environment which jeopardizes the ability of nongovernmental organizations to provide assistance to Gaza's most vulnerable residents.

The official, who declined to be named, said Hamas had demanded access to files and records of NGOs, which would reveal financial and administrative information, details of staff members and information on beneficiaries.

He said that Hamas had shut down the International Medical Corps (IMC) an NGO and USAID partner organization, after its officials objected to unwarranted audits.

We are disappointed that Hamas has once again chosen to put its political agenda ahead of the welfare of the Palestinian people, the official said, calling on the group to cease its interference ... so that we can resume our humanitarian and development activities in Gaza.

Palestinian-based NGOs funded by the European Union have in the past also complained of Hamas meddling in their affairs.

Hamas administration official Taher al-Nono said an understanding had been reached which would allow independent auditing teams to inspect the files of NGOs, but he added that Hamas had the right to monitor their work in the territory.

The IMC will be allowed to reopen its offices on Saturday or Sunday, he added.

Responding to the USAID decision to suspend its partner organizations' work, Nono said Such a decision sounds odd a day after the understanding was reached ... we reject any foreign intervention in Palestinian affairs.

The U.S. official said some 600,000 Gazans -- about a third of the population of the coastal strip -- were receiving some $98 million worth of assistance from USAID projects in health, education, construction and infrastructure.

Washington has designated Hamas as a terrorist group and it is shunned by the West for spurning permanent coexistence with Israel. The group seized control of the Gaza Strip from Palestinian President Mahmoud Abbas's Fateh faction in 2007.

Western-backed Abbas holds sway in the Israeli-occupied West Bank. Palestinians want both territories for a future state with Arab East Jerusalem as its capital. (Writing by Ori Lewis in Jerusalem, editing by Tim Pearce)