European Union foreign policy Chief Josep Borrell has said negotiations to bring Iran and the US back into the nuclear deal curbing Tehran's nuclear programme in exchange for lifting sanctions are in stalemate.

In a statement, Borrell said political situation in the US, and inconclusive directions seem to prolong the statement.

The European parties to the nuclear deal, Britain, France and Germany, last week expressed “serious doubts” about Iran's sincerity in reviving the pact.

On the other hand, Iran called the joint declaration unconstructive and regrettable.