A stern US warning to international financial institutions has made it impossible for the Palestinian Authority to receive funding since the Islamic Hamas group took power, a top Palestinian official said Saturday. It was the first time a Palestinian official has admitted the US has influenced financial institutions. Israel, the United States, the European Union, Canada and other countries have frozen financial assistance to the Palestinian Authority since Hamas took power last month after sweeping January parliamentary elections. In an attempt to help the cash-strapped Palestinian Authority make ends meet, Arab countries pledged to give the Palestinians $55 million in monthly aid. But the United States has given orders to banks not to transfer money to a Hamas-led Palestinian government, Nabil Amr, a top aide to Palestinian President Mahmoud Abbas, said.