LISBON (Reuters) - Portugal is likely to extradite former CIA officer Sabrina de Sousa next week to Italy, where she has been convicted in absentia over the kidnapping of an Egyptian cleric, on condition that she is retried, her lawyer said on Thursday.

De Sousa, who is a dual U.S.-Portuguese citizen and denies involvement in the abduction, was detained by Portuguese police on Monday and is awaiting extradition in a prison in Porto. Italian prosecutors want her to serve a six-year sentence.

She was one of 26 people convicted in absentia on charges of snatching Hassan Mustafa Osama Nasr from a street in Milan in 2003 and taking him to be questioned in Egypt under the U.S. "extraordinary rendition" programme.

The programme was one of Washington's most controversial responses to the Sept 11, 2001, al Qaeda attacks. Nasr, who was on a U.S. list of militant suspects, said he was tortured under interrogation after he was transferred to Egypt.

"Over the course of next week, Sabrina should be moved to Italy," said her Portuguese lawyer, Manuel de Magalhaes e Silva, adding that her arrival in Italy will pose a dilemma for the Italian judiciary and it was not clear whether she would serve time in jail.

"What will an Italian judge do when he faces a detainee who has been extradited after a Portuguese court authorised it under the condition that there will be a second trial, while under Italian law that will be difficult to have?" he asked.

The Portuguese Justice Ministry would not comment.

A White House official said that Washington was "deeply disappointed in Ms. de Sousa’s conviction and sentence, and we are following her case closely... The U.S. government takes its obligation to assist U.S. citizens overseas seriously."

"We appreciate the efforts of the Italian government to challenge the prosecution before the Italian Constitutional Court," said the official, adding that the State Department has been in touch with de Sousa.

The CIA declined to comment on the case.

De Sousa's lawyer told the RTP television channel that "the very least that is expected from the U.S. diplomacy is that it works with the criminal (authorities in Italy) for the situation to be resolved swiftly, at least via a presidential pardon."

Some of the people convicted in Italy for being involved in the rendition of the Egyptian cleric have been pardoned.

De Sousa, who left the CIA in 2009, was briefly arrested in Portugal in October 2015 at the request of Italian prosecutors. Her passports were confiscated, but she was quickly released.

Several of her appeals to Portuguese authorities against the extradition failed over the course of last year.

(Reporting By Andrei Khalip and Mark Hosenball; Editing by Dominic Evans)