An accused leader of a major drug cartel pleaded not guilty to cocaine charges Monday, a month after the Coast Guard arrested his younger brother in international waters off the Mexican coast.

Francisco Rafael Arellano Felix, one of seven brothers suspected of being behind the Tijuana-based Arellano Felix cartel, is accused of selling about a half-pound of cocaine to an undercover police officer in a San Diego motel in 1980.

Arellano Felix, 56, said nothing during a brief hearing in San Diego federal court. A federal defender entered not guilty pleas on his behalf to one count of distributing cocaine and one count of conspiracy to distribute cocaine.

The government would consider dropping charges against Arellano Felix if he cooperates with authorities in other cases linked to the cartel, U.S. Attorney Laura Duffy told reporters. Each of the two counts carries a maximum sentence of 15 years in prison, Duffy said.

Arellano Felix fled San Diego before facing trial on the cocaine charges. He was arrested in December 1993 in Tijuana and served a 10-year prison sentence in Mexico for violating that country's weapons laws.

U.S. authorities requested his extradition in 2003, and a Mexican judge approved it in 2004. He was remanded to U.S. custody in Brownsville, Texas, on Saturday.

The extradition comes one month after Francisco Javier Arellano Felix, 36, was captured by the Coast Guard aboard a sport-fishing yacht in international waters off La Paz, Mexico, and taken to San Diego to face drug charges.

The younger Arellano Felix has pleaded not guilty to drug trafficking, money laundering and conspiracy charges.