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LISBON, Portugal — A former CIA agent will be handed over to Italy in the coming days to serve a four-year prison sentence after being convicted of involvement in a U.S. program that kidnapped suspects for interrogation, a lawyer said Tuesday.

Sabrina De Sousa, 61, was among 26 Americans convicted of kidnapping suspect cleric Osama Moustafa Hassan Nas, also known as Abu Omar, from a Milan street on Feb. 17, 2003. She denied involvement in the abduction.

The U.S. rendition program, under which terror suspects were kidnapped and transferred to centers where they were interrogated and tortured, was part of the anti-terrorism strategy of the Bush administration following the Sept. 11, 2001, attacks. Former President Barack Obama ended the program years later.

Sabrina de Sousa in 2012. Nikki Kahn / The Washington Post/Getty Images

De Sousa spent the night in a women's prison near Lisbon Monday after a Portuguese court ordered police to extradite her, her Portuguese lawyer, Manuel Magalhaes e Silva, told the Associated Press in an interview.

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He said she was detained after a two-year fight against extradition and would be put on a plane once formalities between Portuguese and Italian police were finished.

Speaking with NBC News, Silva expressed concern that De Sousa would be denied the second trial that he claimed was a condition of her extradition.

"Last May, a Portuguese court ruled that she could be extradited to Italy on condition that she would be granted a second trial, as she was convicted in absentia," Silva said. "But the Italians are now saying that this won’t be the case as her lawyer attended the trial until the end even if she wasn’t there, so she should just serve her four years sentence."

He added: "The Italian court sentenced her on the basis of a 17-seconds-long telephone call she received by another agent who was later involved in the extraordinary rendition of Abu Omar, and on the assumption that, as she held a senior position in Italy at the time, she couldn’t not know what was going on."

The U.S. government expressed concern with De Sousa's treatment.

"We are deeply disappointed in her conviction and sentence," acting State Department spokesman Mark Toner said in a statement. "This is a matter that U.S. officials have been following closely. We have asked our European counterparts what their next steps may be, but we are not in a position to detail those discussions."

Cleric Osama Hassan Mustafa Nasr, who is also known as Abu Omar. Amr Nabil / AP

De Sousa lost several appeals against extradition since her arrest at Lisbon Airport in October 2015 on a European warrant. She had argued she was never officially informed of the Italian court conviction and couldn't use confidential U.S. government information to defend herself.

Once in Italy, De Sousa is expected to be taken to a women's prison in Milan, but her Italian lawyer Dario Bolognesi said he would immediately appeal to the Milan court to defer her imprisonment pending a decision on her years-long request for clemency. Other Americans convicted in the case have received clemency from the Italian president.

Silva, De Sousa's Portuguese lawyer, told NBC News that her lawyer in Italy had already reached out to the Italian president to ask for an official pardon.

De Sousa, who was born in India and holds both U.S. and Portuguese passports, has said she had been living in Portugal and intended to settle there.

She was on her way to visit her elderly mother in India with a roundtrip ticket when she was detained.