China executed a convicted Japanese drug smuggler yesterday, making him the first Japanese citizen to be put to death in the country since diplomatic ties were re-established in 1972.

Mitsunobu Akano, 65, was executed in the northeastern province of Liaoning, Xinhua news agency reported, quoting an announcement from China's top court, the Supreme People's Court.

Tokyo confirmed the execution had taken place, saying Chinese officials had informed Japanese diplomats shortly afterwards.

Japanese Prime Minister Yukio Hatoyama again said the case was "regrettable", but Beijing said it hopes relations would not be affected.

"The seriousness of the crime of drug smuggling is widely recognised around the world," foreign ministry spokeswoman Jiang Yu told reporters.

"The death penalty is beneficial to the deterrence and prevention of serious drug trafficking crimes ... we hope this case will not affect the normal development of bilateral ties."

Mr Akano was arrested in September 2006 at an airport in the northeastern city of Dalian while reportedly trying to smuggle 2.5 kilogrammes of narcotics from China to Japan.

"The courts had clear and irrefutable evidence of drug smuggling and the death sentence was handed down and carried out in line with Chinese law," the supreme court said, according to Xinhua.

It added Mr Akano had been "treated legally".

The report said some of the drugs were in the luggage of an accomplice but gave no other details on that person.

Mr Akano was initially sentenced to death in June 2008 and the punishment was upheld last year, Chinese state media have said.