US Vice-President Joe Biden warned on Saturday that the US stands ready to take pre-emptive action against Iran if it does not abandon nuclear ambitions and its support for terrorism.

But in his first major policy speech as President Barack Obama's No 2, Biden also declared the US open for talks with Iran and Russia to repair relations. And he reached out to the world with a promise that the Obama administration will work with allies to solve global problems.

"We will draw upon all the elements of our power - military and diplomatic, intelligence and law enforcement, economic and cultural - to stop crises from occurring before they are in front of us," he told the gathering in his 25-minute address.