ElBaradei's position on Iran has irked the US

A spokeswoman for the International Atomic Energy Agency (IAEA) said all 35 nations on the board of governors approved the move.

The US dropped its objections last week, despite apparent disagreements in the past over Iraq and Iran.

Mr ElBaradei urged Tehran to accelerate its co-operation with the agency, in comments made after his re-election.

"The Iran file will be closed when we close all the issues that are still open," Mr ElBaradei told reporters.

"We are inching forward, but I'd like to have more speedy co-operation on the part of Iran."

Spotlight on Iran

The 62-year-old Egyptian lawyer was the only candidate for the post, which he has held since 1997.

His re-appointment was held up for months by US opposition.

Washington wants him to report Iran to the UN Security Council for trying to hide its nuclear activities.

But Mr ElBaradei has said the "jury is still out" on whether Tehran is secretly developing nuclear weapons, because he has no clear proof.

However, he has also stressed that it is up to Iran to dispel doubts about its programme "through absolute transparency measures and co-operation with the [IAEA]".

This week's IAEA board meeting in Vienna will also hear a report on Iran's nuclear programme.