Any decision by Israel on whether to attack Iran in a bid to halt its nuclear programme remains "very far away," Defence Minister Ehud Barak told army radio on Wednesday.

"We don't have a decision to go forward with these things. We don't have a decision or a date for taking such a decision. This whole thing is very far away," he said.

Asked to explain what he meant by "far away," Barak said he did not want to make "forecasts."

Barak's comments came as tensions rise over Iran's nuclear programme, which Israel and Western governments suspect masks a drive for a weapons capability.

Iran denies any such ambition, saying the programme is for peaceful power generation and medical purposes only, and has refused repeated UN Security Council ultimatums to suspend uranium enrichment.

Israel, which has the Middle East's sole if undeclared nuclear arsenal, has said an Iranian nuclear weapons capability would pose an existential threat to the Jewish state.

It has not ruled out resorting to military action to prevent any possibility of the Islamic republic developing one.

The United States, which has expressed serious concern over Iran's nuclear programme, has pushed for much tougher sanctions, targeting its oil exports and financial institutions.

But Israeli officials have accused Washington of dragging its feet, with Prime Minister Benjamin Netanyahu saying the sanctions currently in force do not go far enough.