Four Pakistanis, including three women, were arrested by Customs authorities in Colombo for smuggling a total of 1.5 kg of heroin into the country by keeping the contraband in their stomach and rectum, an official said on Sunday.

"The four Pakistani nationals had arrived here on Thursday and were arrested at the Katunayake international airport," police spokesman Ranjith Gunasekara told PTI.

The suspects were admitted to the Negombo hospital near here on the same day, he said. Three of them had swallowed the contraband kept in thin rubber cases and that went to their stomach while the fourth — a woman — kept it in her rectum.

The drugs weighed 1 kilogram and 492 grams and have a value of 7.5 million dollars, he said.

"The doctors removed the packets of heroin along with the rubber cases," Mr. Gunasekara said adding, the four were in the hospital for the last three days.