COLOMBO: Sri Lankan customs agents claim to have seized 250 kilograms of heroin worth $19 million from a container sent from Pakistan, in what an official says was the largest-ever stock of heroin nabbed in South Asia.

Customs director Mali Piyasena says the heroin was found Friday at a terminal in the capital, Colombo. The heroin was concealed inside 17,500 small grease cans packed into a large container sent from Karachi.

Piyasena says a Pakistani national and three Sri Lankans were arrested in connection to the seizure and will be handed over to the police narcotics division after the completion of a customs investigation.

He says it was the largest-ever haul of heroin seized in South Asia.

Officials say Pakistan is primarily a transit country for opiates and heroin produced in Afghanistan and over 200 tonnes — estimated to be worth between $25 and $30 billion — annually passes through Pakistan “safely”.

According to a report published in Dawn, Pakistan customs officials say between 210 and 240 tonnes of heroin was smuggled from Afghanistan and reached the global market after passing through Pakistan in the year 2011.