MEXICO CITY, May 11 (Reuters) - The U.S. Treasury on Wednesday said veteran drug lord Rafael Caro Quintero is continuing to traffic illegal drugs since being released from a Mexican prison and it named his common-law wife as a key accomplice.

Caro Quintero, convicted of ordering the torture and murder of a U.S. anti-drugs agent in Mexico in 1985, was freed from prison in August 2013 in a move that angered the U.S. government. He then went underground.

On Wednesday, the Treasury's Office of Foreign Asset Control (OFAC) added his partner, Diana Espinoza Salazar, to its list of drug traffickers, saying she was an integral part of Caro Quintero's ongoing operations, according to a statement.

Espinoza Salazar met the accused drug trafficker in prison and she holds some of his assets under her name, the statement said. OFAC ordered her U.S. assets to be frozen.

OFAC said that Caro Quintero "has continued to engage in drug trafficking activities since his release."

"Treasury, in coordination with DEA (Drug Enforcement Administration), is committed to targeting Caro Quintero until he is brought to justice and his organization is dismantled," said Acting OFAC Director John E. Smith.

Caro Quintero, who is believed to be 63, is one of the old guard of the countries' drug lords. He was one of the leaders of the Guadalajara cartel, a forerunner of Joaquin "Chapo" Guzman's Sinaloa cartel.

Guzman was moved to a prison near the U.S. border last weekend and on Monday a court said that he can be extradited to face charges in the United States.

Caro Quintero had served 28 years of a 40-year sentence for the brutal death of DEA agent Enrique Camarena and was released after a Mexican court ruled he should have been tried at a state level rather than on federal charges.

The United States is offering a $5 million dollar reward for information leading to Caro Quintero's recapture.

Following his release in 2013, the United States asked Mexico to detain him so that he could be extradited to the United States. (Reporting by Anahi Rama; Editing by Andrew Hay)

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