Bill Richardson, left, and journalist Paul Salopek, walk to a conference room in Albuquerque, N.M.,after their arrival in US, September 10, 2006

An American journalist who was held by Sudan on charges of espionage has returned to the United States.

Chicago Tribune journalist Paul Salopek arrived in his home state of New Mexico Sunday after more than one month in a Darfur prison.

Following his release Saturday, Salopek thanked all those who had worked to free him. He said he was treated well during his detention.

Salopek's driver and interpreter were also freed and were to return to Chad.

A U.S. state governor, Bill Richardson of the southwestern state of New Mexico, said he had secured their release on humanitarian grounds during talks with Sudanese President Omar al-Bashir in Khartoum Friday.

Salopek was in Darfur on an assignment for National Geographic magazine when Sudan detained him on charges of espionage, passing information illegally, writing false news and entering without a visa.

He is a Pulitzer prize-winning reporter for the Chicago Tribune.

In 1996, Richardson successfully negotiated the release of a U.S. pilot and two Red Cross workers held by Sudanese rebels for 38 days.