China has executed four criminals involved in drug production cases in an effort to crack down on drug supply sources, the Supreme People's Court (SPC) said Tuesday.

Liu Zhaohua was executed Tuesday morning in south China's Guangdong Province for making 12,660 kilograms of methamphetamine, commonly known as "Ice", and 15 kg of amphetamine from 1995 to 1999.

The Intermediate People's Court of Guangzhou in the provincial capital of Guangdong said Liu was involved in making, trafficking and selling "an especially large amount" of drugs and induced "huge social harm."

Liang Ruinan, also executed Tuesday morning, was caught carrying 42.58 grams of methamphetamine and 9.45 g of tablets which contained methamphetamine and caffeine on April 2, 2006 in Beijing.

Liang was also found to be responsible for making a total of 166.45 kg of methamphetamine liquor jointly with six further suspects, of whom three are still at large.

The other cases occurred in southwest China's Sichuan Province, and involved a total of 68.81 kg of Ketamine powder and 9.7 litersof Ketamine liquid compound.

Zhang Jianxun and He Qibin who were found guilty in these cases were sentenced to death and executed earlier. The SPC did not reveal the times or locations of the executions.

A death penalty is usually imposed by local courts and subject to review and approval by the SPC.

According to the SPC, courts across China handled 14,282 drug-related cases between January and May, up 12 percent over the same period last year. In those cases, 6,379 people were convicted and received severe penalties, ranging from five years' imprisonment to capital punishment.

(Xinhua News Agency September 16, 2009)