A UN agency operating in the Gaza Strip said Friday that it thinks the territory's Hamas rulers have delivered a letter to President Barack Obama through a visiting US senator. Sen. John Kerry visited Gaza on Thursday, the highest-level visit by a US official since the Hamas terror group seized power there nearly two years ago. The UN Relief and Works Agency said Friday that a letter for Kerry was delivered to its compound, and agency spokesman Christopher Gunness said "we think it is from Hamas." He had no details on why UNRWA thought the letter was from Hamas or what it said. "We're very polite. We don't open other people's mail," Gunness said. "We gave it to Kerry to take to Washington." Hamas spokesman Fawzi Barhoum denied the group delivered any such letter. "Although the Hamas movement is eager to communicate with the international community ... we deny delivering any letter to US Congress member John Kerry for him to transfer it to any party," he said.