The Iranian Supreme Leader, Ayatollah Ali Khamenei, has said he supports diplomatic contact between his country and the United States - but added some of it was "not proper" and he did not trust the US.

The comments on Saturday, reported by ISNA news agency, were his first since the Iranian President, Hassan Rouhani, spoke by telephone to his US counterpart, Barack Obama last week.

The call capped a week of overtures to the West by Rouhani and his foreign minister, Mohammad Javad Zarif, during the United Nations general assembly held in New York.

Khamenei said: "We support the government's diplomatic movements and place importance on diplomatic efforts, and support what was in this last trip."

"Of course, in our opinion, some of what occurred in the New York trip was not proper."

"While we are optimistic about our government's diplomatic staff, we are pessimistic about the Americans. The US government is not trustworthy, is self-important, and breaks its promises."

The landslide election in June of Rouhani has raised hopes of a negotiated settlement to Tehran's long-running dispute with the West over its nuclear policy - though it is Khamenei who will make the final decision on the particulars of any deal.

Source: Agencies