Colombia police said they have arrested two men who had each ingested about $40,000 before trying to enter the country, in what may be a novel form of money laundering.

The men were detained separately during the past week at the international airport in Colombia's second city of Medellin and were on flights arriving from Costa Rica, according to security officials.

In the past, "mules" have used a similar method to secret contraband narcotics out of the country, swallowing packets of drugs worth thousands of dollars for sale in lucrative overseas markets.

But authorities said they were unfamiliar with use of the same technique to sneak cash into the country.

"This type of money laundering activity is new in Colombia," said Wilson Patino, a regional immigration director based in the state of Antioquia in northwestern Colombia.

The two suspects, a Colombian and a Venezuelan, were described as being about 35 or 40 years old. Both were said to be heavy-set men whose capacious stomachs apparently did not have much difficulty accommodating the wads of illicit currency.

Officials did not immediately provide details about how the cash was recovered, but did describe how one of suspects came to be arrested.

The Colombian man drew the attention of authorities over the weekend, they said, when he appeared to be nervous and agitated while going through airport security.

He was asked to pass through a scanner again, when the X-ray revealed numerous unusual items in the abdominal area. These turned out to be about 40 capsules, each containing $1,000, officials said.

Authorities believe drug traffickers were the authors of the unusual plot, although they have not ruled out the involvement of other organized crime syndicates, possibly those engaged in arms or human trafficking.

Medellin is the home base for various crime networks, including some involved in the country's flourishing drug trade.

[Image via Agence France-Presse]