British drugmaker GlaxoSmithKline is facing fresh bribery allegations in Syria in a further blow to its reputation after China launched an investigation into the company on similar grounds.

Reuters, citing an anonymous email sent to the company's top managers, reported that GSK allegedly bribed Syrian doctors and officials to boost sales of its medicines. It comes after accusations that the company engaged in malpractices in its non-prescription business in the country.

The email dated 6 August claimed that GSK paid bribes to doctors and officials in the country in the form of cash, trips and free medical samples.

"GSK has been engaging in multiple corrupt and illegal practices in conducting its pharmaceutical business in Syria," according to the lengthy email addressed to Chief Executive Andrew Witty and Judy Lewent, chair of GSK's audit committee.

Following the allegations, GSK said it will launch a probe into the matter. The company has also suspended relations with its Syrian distributors pending results of the probe.

"All the claims in this email will be thoroughly investigated using internal and external resources as part of our ongoing investigation into operations in Syria," a spokesman for the drugmaker told Reuters.

"We are committed to taking any disciplinary actions resulting from the findings. We have suspended our relationship with our distributors in the country pending the outcome of our investigation."

The allegations of corruption in Syria involve relatively small sums of money, compared to the hundreds of millions of dollars the company allegedly paid to Chinese doctors and officials. GSK generates sales of less than £6m ($10m, €7.5m) per year in Syria, compared to its total sales of £26.5bn in 2013.

However, the growing number of bribery claims against the company in various countries is damaging the company's reputation.

In addition to the far reaching bribery scandal in China, GSK is facing similar allegations in Iraq, Jordan, Lebanon and Poland.

The US Department of Justice is investigating the New York Stock Exchange-listed company for possible breaches of the Foreign Corrupt Practices Act (FCPA). Meanwhile Britain's Serious Fraud Office has launched a formal criminal investigation into its overseas activities.