British drug giant, GlaxoSmithKline admitted that some of its executives in China appear to have violated Chinese law in a bribery and corruption scandal which has hit the firm.
GSK is being investigated by Chinese police for alleged corruption, price fixing.
"Certain senior executives of GSK China who know our systems well, appear to have acted outside of our processes and controls which breaches Chinese law," Abbas Hussain, GSK's international president said in a statement.
GSK is the latest in a string of multinationals to be targeted by Chinese authorities over alleged corruption, price-fixing and quality controls.
Chinese police last week accused GSK of bribing officials and doctors to boost sales and raise the price of its medicines. They said GSK transferred up to 3 billion yuan ($489 million) to 700 travel agencies and consultancies over six years to facilitate the bribes. Four senior Chinese executives from GSK have been detained. Britain's biggest drugmaker has said it was deeply concerned by the allegations, which it called "shameful".
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Chinese police have detained four China-based GSK executives and have prevented Steve Nechelput, the firm's finance director from leaving the country.
The pharmaceuticals firm said it had "zero tolerance for any behavior of this nature" and would overhaul its operations in China. That would help make its medicines more affordable to Chinese patients, it said.
"I want to make it very clear that we share the desire of the Chinese authorities to root out corruption wherever it exists. We will continue to work together with the MPS (Ministry of Public Security) and we will take all necessary actions required as this investigation progresses," added Hussain.
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Chinese police have also visited the Shanghai office of British drugmaker AstraZeneca, following allegations against GlaxoSmithKline.
An AstraZeneca spokeswoman said on Monday that police had visited on Friday and taken away one employee for questioning.
"We believe that this investigation relates to an individual case and while we have not yet received and update from the Public Security Bureau, we have no reason to believe it's related to any other investigations," she said.
"AstraZeneca is committed to acting with integrity at all times and in all of our operations and interactions around the world. AstraZeneca adheres to high ethical standards in the pharmaceutical industry, and does not tolerate any illegal or unethical conduct in our business activities," she added.
GSK and AstraZeneca shares were slightly lower in mid-morning trade on Monday.
—By CNBC's Jenny Cosgrave: Follow her on Twitter @jenny_cosgrave