"Clearly, we are likely to see some impact to our performance in China as a result of the current investigation," said GSK CEO Sir Andrew Witty, "but it is too early to quantify the extent of this."
Sine the bribery allegations first surfaced, GSK's share price has slumped 3.5% in London and 2.4% on the New York Stock Exchange.
What are the penalties if GSK is found guilty?
China's investigation could expose the company to legal action in the U.K., and possibly the United States, under laws relating to the bribery of foreign public officials.
GlaxoSmithKline says it has informed the U.K.'s Serious Fraud Office about the bribery allegations but had not yet been asked to provide any further information. The agency, which investigates and prosecutes corruption cases, said last week that it could neither confirm nor deny an interest in the claims against GSK at this stage.