Iran's enemies seek to disrupt the "calmness" in the country through economic confrontation, supreme leader Ayatollah Ali Khamenei said on Monday in an address delivered in the northeastern city of Shirvan.

The fiery speech comes as the European Union is about to ratchet up sanctions against Iran over its disputed nuclear drive and as an oil embargo by the United States and EU begins to impact on the Islamic republic's economy.

"I am asking officials in the judiciary, executive and legislative branches to be watchful so the the illwishers (Western powers) are not able to disrupt the calmness in the country with their plots," Khamenei said his address, which was broadcast live on television.

"With God's grace, as was the case in other issues which the enemies were not able to do anything, they can do no damn thing in their economic confrontation with our people," he added.

Khamenei urged Iranian officials to focus on economic issues that the "enemies" want to use to weaken Iran.

Last Wednesday, the supreme leader railed against the sanctions, labelling them as "barbaric."

"This is a war against a nation... But the Iranian nation will defeat them," he said, as economists said the sanctions were contributing to falling oil exports, a sliding currency, soaring inflation, slipping industrial output and rising unemployment.

In Luxembourg, British Foreign Secretary William Hague said Monday the 27-nation EU was mulling new sanctions.

"Today we expect to agree fresh sanctions on Iran as a result of its nuclear programme and its continued failure to satisfy the world that that programme is for peaceful purposes," Hague said.

The new package of sanctions is expected to target EU dealings with Iran's banks, as well as trade and gas imports, diplomatic sources said.

After long denying the impact of Western economic sanctions against Iran, Iranian leaders since last summer have changed their rhetoric and now regularly condemn the Western imposed "economic war" against Iran.

They acknowledge that the economy is suffering in particular due to the cut in oil exports and production, the main source of the country's revenue.

All Iranian officials, however, have repeatedly maintained that Tehran will not give its nuclear programme despite sanctions.

The West suspects Iran is seeking to build atomic weapons under cover of a civilian nuclear programme, a charge vehemently denied by the Islamic republic.