China executed a convicted Japanese drug smuggler on Tuesday, 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 that Chinese officials had informed Japanese diplomats of the execution shortly after it took place. Japanese Prime Minister Yukio Hatoyama again said the case was "regrettable".
Akano was arrested in September 2006 at an airport in the northeastern city of Dalian while reportedly trying to smuggle 2.5 kilograms (5.5 pounds) 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," Xinhua quoted the announcement saying.
It said 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.
Officials at China's supreme court did not immediately respond to a request for comment.
Akano was initially sentenced to death in June 2008 and the punishment was upheld last year, Chinese state media have said.
Hatoyama, speaking Tuesday before receiving confirmation of the execution, said: "It is regrettable from the Japanese point of view, even if the legal systems are different. But there isn't much that Japan can do about this."
Justice Minister Keiko Chiba expressed concern that the case "could trigger a backlash from the Japanese public", according to Jiji Press.
Beijing has informed Japan it plans to execute three more Japanese drug smugglers as early as Thursday -- Teruo Takeda, 67, from Nagoya city; Hironori Ukai, 48, from Gifu prefecture; and Katsuo Mori, 67, of Fukushima prefecture.
Japan uses capital punishment, usually in cases involving multiple homicides.
Last week, rights group Amnesty International called on Beijing to say publicly how many people it puts to death each year, saying the figure was likely in the "thousands" and more than the rest of the world combined.
Such data is not released by China, where it is considered a state secret.
In December, China executed Briton Akmal Shaikh, a 53-year-old father-of-three convicted of drug smuggling. Supporters said he was mentally ill and London repeatedly urged Beijing to grant clemency.
China has slowly been reforming its death penalty system after acknowledging several miscarriages of justice.
At the beginning of 2007, the Supreme People's Court began reviewing every death penalty case rather than allowing lower courts to issue the final judgement -- a move that China says has led to fewer executions.
Amnesty's Japanese chapter said China's capital punishment system had "many serious problems" and called on Beijing not to follow through with the executions of the three other Japanese nationals.
