British drugmaker GlaxoSmithKline said on Monday it had stopped using all travel agencies which have been accused by the Chinese police of channelling bribes to illegally boost sales and inflate the price of its medicines in the country.

Chinese police had said earlier in the day that four senior Chinese executives from the firm had been detained as part of the probe.

"GSK shares the desire of the Chinese authorities to root out corruption," it said in a statement. "These allegations are shameful and we regret this has occurred. We are taking a number of immediate actions.

"We are reviewing all third party agency relationships. We have put an immediate stop on the use of travel agencies that have been identified so far in this investigation and we are conducting a thorough review of all historic transactions related to travel agency use."

(Reporting by Kate Holton; Editing by Mark Potter)