TEHERAN (AFP) - Iran's most senior leader said on Thursday he is not optimistic but also "not opposed" to direct talks with arch-foe the United States over Teheran's disputed nuclear programme.

"The Americans have sent messages to have a direct nuclear dialogue on the sidelines of the talks" with the so-called P5+1 group of world powers, said supreme leader Ayatollah Ali Khamenei in a live televised address.

"I am not optimistic but I am not opposed to it," said Khamenei, who has the final say on Iran's atomic drive.

He was referring to US offers of direct talks with Iranian officials on the sidelines of ongoing diplomatic efforts by itself, Russia, China, Britain, France and Germany aimed at finding a solution to the nuclear stand-off.