(CNN) -- Libya said Saturday it will seek extradition of its former spy chief who was arrested in Mauritania and is wanted for war crimes by the International Criminal Court. Mauritanian security authorities arrested Abdullah al-Senussi, Libya's former chief of intelligence and one of the Gadhafi regime's most wanted men. Al-Senussi, the late Moammar Gadhafi's brother-in-law, was arrested Friday evening at Nouakchott airport, a Libyan transitional government spokesman said. He was carrying a fake passport from Mali at the time of his arrest. France is also in the process of requesting al-Senussi's extradition from Mauritania, President Nicolas Sarkozy's office said.
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NEW: U.S. Rep. Nancy Pelosi is in Libya to lead a congressional delegation
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Al-Senussi was arrested at an airport in Mauritania on Friday, Libyan authorities said
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He was the intelligence chief for Libya's Moammar Gadhafi
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He is wanted by the International Criminal Court
Pelosi, who is leading a congressional delegation that traveled to @placeholder on Saturday, said al-Senussi's detainment could bring some form of "closure," which she described as "very important."