WASHINGTON (AFP) - US President Barack Obamas administration wrote to Irans supreme leader Ayatollah Ali Khamenei before the disputed elections offering to improve relations, a report said Wednesday. The Washington Times cited an Iranian with knowledge of the overture as saying that the letter was sent between May 4 and 10 and suggested regional and bilateral cooperation and talks on Irans nuclear programme. An administration official declined to talk about the letter, but did not deny its existence, a day after Obama fired off his most overt condemnation yet of the Iranian governments suppression of post-election demonstrations. The official added however that the Obama White House had indicated for a long time that it wanted to talk to Iran, and had sought to communicate in a variety of ways. The Times report said the letter was passed to the Iranian Foreign Ministry by a representative of the Swiss embassy, which takes care of US interests in Iran, as the two arch-foes have no diplomatic relations. It said the supreme leader had confirmed the existence of the letter in an oblique reference during his speech last week.