Iran's Supreme Leader Ayatollah Ali Khamenei speaks live on television after casting his ballot in the Iranian presidential election in Tehran June 12, 2009. REUTERS/Caren Firouz/File Photo

(Reuters) - Iranian Supreme Leader Ayatollah Ali Khamenei said on Saturday it would be an “obvious mistake” to negotiate with the United States as Washington was unreliable.

“The word and even the signature of the Americans cannot be relied upon, so negotiations with America are of no avail,” Khamenei said in a meeting with Foreign Ministry officials, adding that negotiations with Washington would be an “obvious mistake”, according to his official website.