MEXICO CITY (AP) _ The army general appointed to bring toughness and integrity to Mexico's war on drugs has been arrested on suspicion of taking bribes to protect a leading drug lord, less than three months into his new job.

The ouster of Gen. Jesus Gutierrez Rebollo shook Mexico's military and political establishment and dismayed the United States' own drug czar, who had lauded Gutierrez's ``reputation of impeccable integrity'' when the career army man was appointed to head the National Institute for Combating Drugs.

Defense Secretary Gen. Enrique Cervantes Aguirre announced Gutierrez's firing and arrest at a news conference Tuesday night, while Gutierrez was in a military hospital recovering from an apparent heart attack suffered when authorities confronted him with the evidence against him.

``This is very painful for us to report,'' Cervantes Aguirre said _ a statement echoed by President Ernesto Zedillo, who called it ``concealment and deceit ... and betrayal of the army.''

Authorities said a number of law enforcement officials and military officers who worked with Gutierrez were also under arrest, but gave little additional information.

Gutierrez and his associates are suspected of receiving money and favors from Amado Carrillo Fuentes, one of Mexico's most notorious drug lords. Mexicans call Carrillo Fuentes the ``Lord of the Skies'' because he uses an airplane to transport illegal drugs across the border into the United States.

By U.S. estimates, three-quarters of the South American cocaine smuggled into the United States goes by way of Mexico.

Gutierrez's appointment had been seen as an encouraging sign that the military _ generally considered less corruptible than civilian drug agents _ would take on a larger role in Mexico's war against drugs.

The revelations on his alleged double-dealing come at a particularly delicate time in relations with the United States. The State Department must deliver its annual certification to Congress on March 1 that Mexico is making its best efforts to combat the drug trade, or Mexico will lose key U.S. aid.

In Washington, U.S. drug policy czar Barry McCaffrey supported Mexico's decision to oust Gutierrez but said he was ``extremely disappointed that corruption may have reached such a level in Mexico.''

``Mexico is taking the right direction,'' said McCaffrey, a retired Army general. ``This demonstrates that Mexico is seriously threatened by corruption and violence but will take strong steps to root them out.''

In December, McCaffrey had welcomed Gutierrez's appointment, saying he ``has a reputation of impeccable integrity, and he is known as an extremely forceful and focused commander.''

Gutierrez, 62, is the first high-ranking Mexican officer ever to be formally accused of involvement with drug traffickers. Cervantes Aguirre said Gutierrez's actions violated national security and set back the fight against drugs.

Cervantes Aguirre said authorities became suspicious earlier this month when Gutierrez moved into a posh apartment in Mexico City, allegedly owned by one of Carillo Fuentes' top lieutenants, Eduardo Gonzalez Quirate.

``On Feb. 6, we received information that General Gutierrez Rebollo had moved into a luxurious apartment in the capital whose rent he could not possibly afford on his salary,'' Cervantes said.

The same day, questioned about the apartment in Cervantes' office, an anxious, upset Gutierrez appeared to have a heart attack.

Besides the alleged payoffs, federal prosecutors say they also are investigating allegations that Gutierrez allowed the transport of drugs, weapons, and smuggled goods.

Over the weekend, a task force of military intelligence officers and federal police raided three homes belonging to Gutierrez and several federal and local police installations in Guadalajara, the capital of Jalisco state and long a center for drug-trafficking.

Gutierrez headed military operations in Jalisco for seven years, and did a credible job tracking down drug traffickers there, Cervantes Aguirre said.

Known as a rigid and moral man, Gutierrez oversaw the 1995 arrest of reputed drug lord Luis Hector Palma Salazar, who allegedly was involved in the 1993 slaying of a Roman Catholic cardinal.

Tito Valencia Ortiz, another army general, has been named to replace Gutierrez as drug czar.