CAIRO (Reuters) - Arab League chief and former Egyptian Foreign Minister Amr Moussa has ruled out running for president of Egypt in elections due to be held in late 2011.

Moussa, who had been tipped as a possible candidate, said in an interview published in Al Masry Al Youm newspaper on Wednesday it was not possible to mount a challenge.

"The question is, is it possible? And the answer is, the road is closed," he said.

Speculation has mounted over who will succeed 81-year-old President Hosni Mubarak, who is expected to seek another term in 2011, health permitting. Mubarak's 45-year son Gamal has been tipped as a possible successor.

Moussa, aged 73 and praised by many Egyptians and Arabs for criticism of both Israel and past U.S. Middle East policies, was quoted in October as not ruling out such a bid.

Analysts say constitutional rules make an independent nomination almost impossible.

If Moussa were to run as an independent, he would need the backing of 250 elected representatives across both houses of parliament and local councils -- all of which are dominated by Mubarak's ruling National Democratic Party.

"I cannot join a party just because it would enable me to be nominated . . . it is against my principles and I consider this to be clear political opportunism," Moussa said.

Running as a independent was a "difficult matter or even impossible," he added.