Mahmoud Ahmadinejad threatened with UN walk out if Holocaust comments repeated

British officials plan to walk out of a United Nations session if Mahmoud Ahmadinejad, the Iranian president, repeats comments which deny the Holocaust.

Andrew Porter, Political Editor

A succession of world leaders including President Barack Obama and Gordon Brown will address the UN in New York today. But Mr Ahmadinejad's presence in America has caused consternation.

Many fear he will provoke outrage by discussing Holocaust denial while the world's media attention is on him. Earlier this year, a similar statement in Geneva saw officials from several countries walk out.

A Number 10 source traveling with the Prime Minister said: "If he does get into Holocaust denial territory or say something that's not compatible with human rights that we work to uphold then we would consider walking out."

Mr Brown will also come face to face with Muammar Gaddafi, the Libyan leader, at a meeting of the UN security council. Libya is a non permanent member of the council.

It will be the first time they have met since the release of the Lockerbie bomber last month. That has led to tension between London and Washington with Mr Obama telling Mr Brown that he was disappointed with the prisoner's release.

Number 10 did not indicate whether the two men would shake hands but it is expected they will if they come face-to-face.

That could further inflame opinion in America where families of Lockerbie victims have protested at Megrahi's release.

On the first day of his four-day trip to America Mr Brown will tell the UN: "Once again we are at a point of no return. And just as the collapse of the banks focused our minds a year ago - so we must now grasp this next set of issues."

Last night the Prime Minister took part in a dinner discussing climate change. He called on leaders to take seriously the drive to secure a new global warming reduction target at Copenhagen in December.

He will say today: "This is the moment, now, to limit and reverse the climate change we are inflicting on future generations. Not later, at another conference, in another decade, after we have lost 10 years to inaction and delay".

His speech will also address nuclear proliferation, poverty in Africa and terrorism.