US and Sri Lankan authorities have seized around 463 kilograms of crystal methamphetamine worth about $21 million in an operation targeting a drug trafficking network allegedly based in Pakistan.

The seizure followed intelligence about suspicious maritime containers being shipped from Pakistan to Colombo, according to the US Embassy in Sri Lanka.

The US Drug Enforcement Administration’s New Delhi office and Sri Lanka’s Police Narcotics Bureau carried out the operation. Intelligence was developed between August 14 and 29 with assistance from Pakistan’s Anti-Narcotics Force.

The drugs were found hidden inside bath towels. Several suspects, including Pakistani nationals, were arrested, according to the US Embassy.

Authorities said the shipment was allegedly being routed through Sri Lanka for distribution in international markets.

The operation was aimed at disrupting a Pakistan-based network involved in international drug trafficking. US authorities said they would continue working with regional partners to target transnational narcotics networks and disrupt their illegal operations.