Egyptian authorities freed opposition politician Ayman Nour on Wednesday after more than three years in prison on forgery charges he said were politically motivated.

Nour told Reuters by telephone from his home that he planned to continue his work in politics through the opposition Ghad party.

"Thanks to God I am released," he said.

"I am going to practice my role as a politician through the Ghad party and through my previous role," he added. His wife, Gameela Ismail, said he intended to resume his post as leader of the party.

Prosecution sources said Nour was released on health grounds.

Nour was jailed in 2005, shortly after coming a distant second to incumbent President Hosni Mubarak in Egypt's first multi-candidate presidential elections.

He said then the Egyptian government was punishing him for daring to challenge Mubarak, who has ruled the most populous Arab country since 1981.

The U.S. administration of former President George W. Bush has called repeatedly on Egypt to release Nour. Cairo says its judiciary is independent and not politically motivated.