SINGAPORE (AP) – Police in Singapore said Thursday they have arrested 13 foreigners, including an American, in an anti-drug operation, less than a week after an Australian was put to death for a narcotics conviction.

Not all of the suspects have been charged. Those who were were charged do not face the death penalty if convicted. The defendants include three Britons, an American, seven Thais, a Malaysian and a Japanese. A Singaporean also was arrested.

Nipaporn Ton-sai, 28, of Thailand, faces up to 20 years in prison if convicted of being a drug syndicate leader and trafficker, according to court documents and a statement from Singapore’s Central Narcotics Bureau. She and her 31-year-old American boyfriend were arrested in the upscale Orchard Road shopping area in a sting operation, officials said.

It was not immediately clear if the American, who was not identified, has been charged. He tested positive for illegal substances, the statement said.

Lionel Rudolf Zupancich, 45, of Britain, faces up to 20 years in jail and 15 strokes of the cane if found guilty of trafficking about a quarter of an ounce of cocaine, court documents showed. Investigators also said Zupancich had the synthetic drug ketamine.

Jason Taylor, 33, also of Britain, could be imprisoned for up to 10 years if convicted of cocaine possession. Japanese executive Jun Terashima, 45, was charged with methamphetamine consumption.

It was not immediately clear if the suspects had entered pleas.

Authorities seized marijuana, Ecstasy, three-quarters of an ounce of cocaine, a third of an ounce of methamphetamine and about a tenth of an ounce of ketamine from the 14 suspects, the Central Narcotics Bureau said.

Singapore has some of the world’s toughest drug laws, including a mandatory death penalty for anyone caught with more than a half-ounce of heroin or more than 17.6 ounces of marijuana. Those convicted are hanged.

The execution of convicted Australian heroin trafficker Nguyen Tuong Van on Dec. 2 drew outrage from Australia’s government and raised international appeals for the tightly controlled city-state to end the mandatory death penalty.