Investigator Peter Humphrey and his wife Yu Yingzeng were arrested by Chinese police in July 2013 following work they did for GSK.
GSK hired Humphrey’s Chinese corporate investigations business, ChinaWhys, in April 2013 to investigate who is behind a suspected smear campaign against the company.
ChinaWhys was hired after a sex tape involving GSK’s former China chief Mark Reilly was sent to senior staff at the company.
Earlier Humphrey noted that accusations that British drug-maker GSK has consistently bribed Chinese doctors to boost the sales of its drugs is ‘credible’.
US Embassy spokesman Nolan Barkhouse was quoted by Reuters as saying that, "We are concerned that consular officers will not be allowed to attend Ms. Yu’s trial in August 2014 despite the fact that under the 1982 bilateral consular convention between our two countries consular officials are permitted to attend such trials."
The British embassy is also said to have engaged with the Chinese authorities about the need for a transparent and fair trial.
The trial is part of investigations into GSK, which Chinese police accuse of funnelling up to CNY3bn ($482m) through travel agencies to bribe doctors and officials.
GSK said in a statement that its China business is now subject to an ongoing investigation by the Chinese authorities with which it is fully cooperating.