US Senator John Kerry, who narrowly lost the 2004 presidential election, entered the Gaza Strip on Thursday in a rare visit by a US elected official.
Kerry, who was the centre-left Democratic Party's previous presidential nominee, met with Karen Abu Zaid, director of the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA).
During the meeting, Zaid gave Kerry a letter addressed to new US President Barack Obama from the Palestinian Islamist militant group Hamas, which seized control of Gaza in 2007, an UNRWA spokeswoman confirmed at UN headquarters in New York.
There was no information about the contents of the Hamas letter.
Kerry chairs the Senate Foreign Relations Committee. His office in Washington could not confirm that Kerry accepted the Hamas letter.
Kerry was travelling with two congressmen, Brian Baird of Washington state and Keith Ellison of Minnesota, both fellow Democrats. In 2006, Ellison became the first Muslim elected to the US Congress.
The trio are the highest-ranking US officials to enter Gaza during the 20 months of Hamas rule. The trip was described as a fact-finding mission to examine humanitarian conditions in the territory, in the wake of a three-week Israeli offensive in December and January against Hamas targets, in response to missile fire into southern Israel by Gaza militants.
Palestinian media reported that the Kerry delegation did not meet with any Hamas representatives.
Kerry met late Thursday with Israeli Foreign Minister Tzipi Livni in Tel Aviv and was scheduled to meet President Shimon Peres on Friday.