Sri Lankan authorities said 22 Buddhist monks were arrested for possession of over 110 kilograms of cannabis – illegal in the South Asian nation – at the international airport in the capital Colombo, the largest ever drug bust at the terminal.

Axar.az informs, citing CNN, authorities said the men, who were returning from Thailand, had suitcases each containing more than five kilograms (11 lbs) of cannabis at the Bandaranaike International Airport.

Police said the operation was carried out based on a tip-off.

They allege the drugs were concealed inside luggage using specially modified false bottoms.

The estimated value of the narcotics is over $3.45 million (1.1 billion rupees), according to the government’s official news portal.

Sri Lanka has severe penalties for drug offenses and airports have deployed technology to detect illegal items, according to the UK Foreign Office. Arrests for drug offenses can result in being held without charge indefinitely and lengthy prison sentences if convicted.

The incident marks the first time Buddhist monks have been arrested at the airport carrying illegal drugs.