The tape sparked a bribery investigation that has damaged the drugmaker’s business in China.
A GSK spokesman confirmed the tape existed but did not comment on how it related to the alleged bribery scandal. In July 2013, Chinese police accused GSK of transferring as much as 3bn renminbi (£283m) through travel agencies to bribe doctors and officials.
In May, Chinese police filed corruption charges against Reilly, who has been barred from leaving China and who could face decades in prison.
China’s investigation into GSK and its scrutiny of numerous other foreign and local drugs companies have frightened foreign pharmaceutical executives so much that some fear they could be jailed and have asked their lawyers if they should temporarily leave the country.
Also in May, Britain’s Serious Fraud Office launched a formal criminal investigation into GSK.
GSK shares ended on 1,564p, down 0.6 per cent.