Two Los Angeles Police Department officers have been charged with repeated sexual assaults on four women while on duty in their squad car and elsewhere, prosecutors and police said on Wednesday.

The veteran officers, James Nichols, 44, and his partner, Luis Valenzuela, 43, were arrested on Wednesday and were slated to be arraigned on Thursday, with prosecutors expected to ask that bail be set at nearly $4 million for each man, according to the district attorney's office.

RELATED: NYPD probes assault claim against Eliot Spitzer; lawyer disputes

An 18-count criminal complaint filed on Tuesday charges both officers with numerous instances of forcible rape, rape by threat to arrest or deportation, sexual battery and forcible oral copulation, among other offenses.

The complaint says the two were armed during the majority of the alleged assaults and that most occurred while they were on duty. Valenzuela was also charged with one count of assault with a firearm for allegedly pointing a gun at one of the victims.

If convicted, the two men each face a maximum sentence of life in prison, the district attorney's office said. They have been suspended without pay since 2013, according to police.

The four women, who were not identified, had all been arrested at various times by Nichols and Valenzuela during drug busts, the D.A.'s office said in a statement.

They ranged in age from 19 to 34 at the time of the alleged assaults, which according to prosecutors began in December 2008 and continued through March 2011.

Prosecutors said both men had been assigned to the LAPD's Hollywood division before they were relieved of duty.

"Any officer that abuses the public's trust is not welcome in the LAPD and we will continue vigorously investigating officers accused of alleged crimes and cooperate fully with the district attorney's office," police Chief Charlie Beck said in a statement.

RELATED: Harvard student says school 'refused to act' when she reported sexual abuse

The Los Angeles Times reported in 2013 that Nichols and Valenzuela were narcotics officers under investigation for allegations that they sexually assaulted at least four women they had arrested or used as informants.

The Times cited a search warrant affidavit as alleging that after coercing the women to get into their squad car with threats of jail, the officers drove their victims to secluded areas where one would demand sex while the other kept watch. The affidavit said that in other cases, the men acted alone.