Police have detained the head of Henan's tobacco authority as part of an ongoing corruption probe.

Zheng Jianmin, director of the provincial tobacco monopoly bureau, has been at the center of an investigation since mid-March due to "economic problems", a source inside the bureau told China Daily.

A special supervision team from the State Tobacco Monopoly Administration has arrived to lead the investigation, and all officials above county level are required to keep their cell phones switched on for 24 hours a day, the source said on condition of anonymity.

Zheng, who was scheduled to retire around the time of his detention, has held his post since 2003.

Insiders say he has a reputation as a shrewd businessman, and is credited with turning around the struggling tobacco industry in Xinzheng, a county-level city under the jurisdiction of Zhengzhou, where he was appointed tobacco bureau chief in the late 1980s.

By 1992, the city was making a profit of more than 1.5 million yuan ($238,000) from the sector, according to official statistics.

Zheng's detention follows the mysterious death of Zhang Mingxian, director of the tobacco monopoly bureau of Shangqiu city in Henan.

The official, who received a promotion in September that made him responsible for the supervision of Henan's tobacco industry, was found lying on a staircase in front of his office building on the morning of March 30.

Police issued a statement that same day on their verified Sina Weibo micro blog that said Zhang had committed suicide by jumping from the ninth floor.

The reason remains unclear, and a publicity official with Shangqiu tobacco bureau told China Daily that the case is under investigation.

Sun Yongjun, a tobacco official in Xiangcheng county and one of Zhang's college classmates, said his friend's body was cremated immediately without an autopsy.

"He was buried the next day in his native village in Jiaxian county. None of his colleagues went to his funeral for fear of being involved," Sun said, adding that he and some classmates went.

Li Zhongkai, director of the Henan tobacco monopoly bureau's planning office, was also detained on Feb 14 on suspicion of taking bribes, China Times reported.

Li's wife was also detained but was bailed soon after, the report added.

Shi Pu, a professor of business management research at Henan University of Economics and Law, said the monopoly status has left the tobacco industry lacking in supervision.

Many growers and retailers agreed, including Wang Weiqin, a retailer in his 40s in Zhengzhou, capital of Henan.

One of his complaints is that he is made to buy unpopular brands of cigarettes whenever he orders best-selling ones from the local bureau.

"If I buy a pack of Zhonghua (high-end cigarettes sold for 60 yuan a pack), at the same time I have to buy at least four packs of Jinqu (a local brand costing 9 yuan a pack)," he said. "I have no choice but to accept it because there is nowhere else where I can purchase cigarettes other than the tobacco monopoly bureau."

Wang Ya'nan contributed to this story.

anbaijie@chinadaily.com.cn