Sen. John Kerry accepted a letter for President Barack Obama from Hamas leaders on Thursday, FOX News learned.

A U.N. relief agency official could not say what the contents of the letter were but said U.N. officials passed the letter to Kerry on behalf of the European- and U.S.-designated terror group.

Hamas has denied leaving a letter at the gates of the U.N. headquarters in Gaza.

Kerry, the 2004 Democratic presidential candidate, was visiting the Gaza Strip on Thursday, along with Democratic Reps. Brian Baird of Washington and Keith Ellison of Minnesota, Congress' only Muslim representative.

The lawmakers were already on a trip to Israel, and crossed into the area dominated by Hamas, which calls for the destruction of the Jewish state. Kerry had not been expected to meet with Hamas officials. 

At a press conference in Sderot, Israel, Kerry, head of the Senate Foreign Relations Committee, said the Obama administration's position on Hamas has not changed from the prior administration. He repeated that stance in Gaza.

"The visit does not indicate any shift whatsoever with respect to Hamas," he said.

While in Gaza, the U.N. Relief Works Agency took Kerry on a tour of homes destroyed in the recent bombing of Hamas targets by Israeli Defense Forces as well as the American School.

Hamas and Israel have been locked in negotiations brokered by Egypt to secure a permanent truce in Gaza. However, the unilateral ceasefire which had been declared by both sides while the negotiations continue looks increasingly unstable as Israeli warplanes have conducted attacks on six suspected weapons-smuggling tunnels in southern Gaza in response to rocket fire.

Kerry is next scheduled to visit Damascus, Syria, and meet with President Bashar Assad. Syrian officials have indicated to FOX News in recent weeks that Syria is ready to act as an interlocutor with Hamas to help secure a permanent ceasefire.

FOX News' Nina Donaghy and Reena Ninan contributed to this report.