Two airport security employees have been arrested on drug trafficking and corruption charges, accused of taking bribes to allow large shipments of drugs to pass through the screening process at Los Angeles airport.

The pair were arrested along with two former airport screeners. Authorities said on Wednesday the screeners allowed drugs to pass through X-ray machine checkpoints in five incidents in exchange for payments of as much as $2,400.

The arrests mark one of the first instances in which employees of the Transportation Security Administration (TSA), which oversees screening checkpoints at airports across the nation, have been accused of complicity in drug smuggling, a spokesman for the agency said.

"The allegations in this case describe a significant breakdown of the screening system through the conduct of individuals who placed greed above the nation's security needs," US attorney Andre Birotte Jr said in a statement.

The four were arrested late on Tuesday and early on Wednesday over incidents that took place between February and July 2011, he said.

In three of the incidents, the drugs were smuggled by a confidential source for the US Drug Enforcement Administration. But on the two other occasions, the airport screeners allowed independently operating smugglers to move through their checkpoints, the indictment said.

It detailed the shipment through airport screening stations of over 40kg (88lb) of cocaine, over 20kg of marijuana and about 4kg of methamphetamine.

In one instance, one of the drug smugglers who had been in touch with an airport screener ended up going to the wrong terminal and was stopped at a checkpoint with 4.9kg of cocaine, the indictment said.

Naral Richardson, 30, who was terminated from his job with the Transportation Security Administration in 2010, was accused of orchestrating the five smuggling incidents.

He was charged with five counts of conspiracy , five counts of possession with the intent to distribute narcotics and two counts of offering bribes to public officials. He and a former screener, along with two current screeners, face a maximum sentence of life in prison if convicted.

TSA spokesman Nico Melendez said he was not aware of other cases where agency screeners had taken bribes for allowing drugs to pass, although the FBI said there was at least one other case where a screener was accused, also in Los Angeles. Authorities could not say if that resulted in a conviction.

In the current case, one of the screeners, 23-year-old John Whitfield, was accused of meeting with a DEA confidential source in an airport bathroom and accepting a $600 bribe – the second half of a $1,200 payment – to allow a meth shipment through his screening station, the indictment said.

The other individuals indicted in the case included Joy White, a 27-year-old TSA screener who was fired last year for an unrelated matter, and current screener Capeline McKinney, 25.

One suspected drug courier was in state custody in the case and another was expected to surrender on Thursday.