Beijing  - China executed one of the nation's most notorious drug barons Tuesday and carried out death sentences on three other drugmakers, state media said.

Former policeman Liu Zhaohua, who became one of China's leading producers of methamphetamines, or "ice," was executed in the southern province of Guangdong after he was convicted of making at least 12.7 tons of the drug, the official People's Daily said.

Beijing-based drugmaker Liang Ruinan was also executed Tuesday after his arrest in April 2006 for possession of 166 kilograms of liquid "ice."

Two other drugmakers were executed recently in the south-western province of Sichuan, the newspaper said.

It said the executions marked a continuation of a government campaign that began before the UN-sponsored international anti-drugs day on June 26 when courts across China executed at least a dozen drug producers and traffickers.

Liu, 44, was sentenced to death on the international anti-drugs day in 2007.

He collaborated with fellow Guangdong-based "King of Ice" Chen Bingxi, who was executed in January, earlier state media reports said.

Liu was born into a poor family in Guangdong's neighbouring province of Fujian, where he won an award for outstanding police service in 1990.

He began making drugs in 1996 at a three-storey building he constructed in his hometown, prosecutors said during his trial.

Police had searched for Liu since 1999 and arrested him in March 2005 after offering a reward of 200,000 yuan (29,300 dollars) for information leading to his capture.

China keeps the number of executions a state secret, but the US-based Dui Hua Foundation, a human rights group, has estimated that at least 5,000 people have been executed annually in recent years, more than in the rest of the world combined.

China claims to have limited the use of death sentences in recent years but retains it for 68 offences, including drug trafficking, serious corruption and other non-violent crimes. (dpa)