The GlaxoSmithKline company logo is seen on the GlaxoSmithKline Plc headquarters in London, UK. Photos: CFP

Mark Reilly, GlaxoSmithKline's former head of operations in China, is helping anti-corruption officials in the country who are investigating allegations of extensive bribery by the drug maker.

"Mark is working closely with the Chinese authorities to conduct a thorough investigation and voluntarily returned to China to help them. Several weeks ago he met with the Chinese authorities in Changsha to provide them with information and assistance," GSK said in an e-mailed statement to the Global Times Wednesday.

"At no point was he detained. Mark remains in China to help further with the investigation should it be required," the company said.

Reilly was replaced as GSK's China head on July 25 after Chinese police accused the drug maker of funneling up to 3 billion yuan ($490 million) to travel agencies to facilitate bribes to doctors and officials.

GSK said at the time that he would continue to help lead its response to the bribery investigation.

In a report by the 21st Century Business Herald on Tuesday, Eddingpharm, a third-party medicine distributor, has been accused of bribing doctors in order to boost sales.

GSK said in the statement that it is "aware of the allegations in media reports about Eddingpharm's marketing practices and takes all allegations of this kind very seriously and will work closely with the relevant authorities to investigate further."

A number of GSK's Chinese employees have been detained, including four senior members of the local management team, though not any foreign nationals working for the drug maker yet.

The police allegations against GSK, laid out in detail on July 15, sent shockwaves through the industry and cast doubt over GSK's ability to ensure compliance standards in fast-growing markets like China.

The crackdown reflects a growing determination by Chinese authorities to stamp out corporate bribery and corruption, which can drive up prices for consumers.

GSK has admitted that some Chinese executives appeared to have broken the law and has said it plans to change its business model to lower the cost of medicines in the country.

Several other international drug makers, including Sanofi, Novartis, AstraZeneca, Eli Lilly and Bayer have also been visited by Chinese officials - and this issue has hit sales in the Chinese pharmaceutical market.

Analysts at Deutsche Bank said on Tuesday that the anti-bribery campaign was likely to last for some time, impacting both multinational and domestic drug companies.

GSK will report third-quarter results on October 23, when the scale of the impact of the affair on its business in China is expected to be revealed.