By Sofia Menchu and Mike McDonald

GUATEMALA CITY (Reuters) - Guatemala said on Wednesday it would deport to the United States software pioneer John McAfee, a former Silicon Valley millionaire who is wanted for questioning in Belize over the murder of a fellow American.

McAfee has been held for a week by immigration officials in Guatemala, where he surfaced after evading officials in Belize for nearly a month. McAfee's lawyers managed to block an attempt to deport him back to Belize.

"Complying with migration law, Mr. John McAfee is to be deported to his country of origin," said Fernando Lucero, a spokesman for Guatemala's immigration office.

Guatemala has been holding McAfee, 67, since he was arrested last Wednesday for illegally entering the country with his 20-year-old Belizean girlfriend.

McAfee said he would be heading to Florida.

"I'll be leaving at 3:30 (p.m.) to Miami," he told Reuters by telephone, after which he left for the airport. "That was the only option I had. I can't take a flight that stops in any other country and there are only two flights going to America today."

Police in Belize want to question McAfee as a "person of interest" in the killing of American Gregory Faull, his neighbor on the Caribbean island of Ambergris Caye.

The two had quarreled at times, including over McAfee's unruly dogs. Authorities in Belize say he is not a prime suspect in the investigation.

The eccentric tech pioneer, who made his fortune from the anti-virus software bearing his name, has been chronicling life on the run in a blog, www.whoismcafee.com.

McAfee claims Belize authorities will kill him if he turns himself in for questioning. He has denied any role in Faull's killing and said he is being persecuted by Belize's ruling party for refusing to pay some $2 million in bribes.

Belize's prime minister has rejected the allegations, calling McAfee paranoid and "bonkers.

Belize police spokesman Raphael Martinez said Belize would still want to question McAfee if he reached the United States.

"He will be just under the good will of the United States of America. He is still is a person of interest, but a U.S. national has been killed and he has been somewhat implicated in that murder. People want him to answer some questions," he said.

"We have good relations with the United States of America and I am sure that we will get to the bottom of it."

(Reporting by Sofia Menchu; Editing by Will Dunham and Philip Barbara)