China's biggest drug distributor says two former executives are the target of a corruption investigation, widening a graft probe that has focused on foreign pharmaceutical makers.

A former vice president of state-owned Sinopharm Group Ltd., Shi Jinming, was detained last week by Shanghai prosecutors for "an investigation in relation to an allegation of corruption against him," a company statement said. It said Shi resigned in December for unspecified personal reasons.

Xu Yizhong, who was a general manager of a Sinopharm subsidiary, also is involved in the investigation, according to the statement released Sunday through the Hong Kong stock exchange. It gave no details of the accusations against the two men.

The announcement follows investigations last year of foreign drug makers on suspicion of paying doctors or other hospital employees to encourage use of their products.

In the highest-profile case, four employees of GlaxoSmithKline PLC were detained. GSK said the employees acted without its knowledge and last month announced an overhaul of its global marketing. It promised to stop paying doctors to promote its products at speaking engagements and scrapped individual sales targets.

Rival drug maker AstraZeneca said one of its executives also was detained by investigators. No further details of that case have been released.