Britain's fraud agency on Tuesday said it had launched a probe into pharmaceutical giant GlaxoSmithKline, which is already subject of a series of investigations into alleged staff corruption. The Serious Fraud Office (SFO) confirmed it had opened a "formal criminal investigation" into the London-based drugs manufacturer's commercial practices. "GSK is committed to operating its business to the highest ethical standards and will continue to cooperate fully with the SFO," said a company spokesman, without providing further details. GSK last month said first-quarter revenues had fallen 10 percent to £5.6 billion (6.9 billion euros, $9.4 billion) after a Chinese corruption investigation impacted sales growth at the company's emerging markets division. In a further blow, Polish prosecutors in April said they had extended a probe into allegations that GSK bribed doctors into promoting one of its drugs. The company is also investigating alleged corruption by staff at its pharmaceuticals division in Iraq. GSK last year admitted that senior employees appeared to have breached Chinese law after Beijing authorities alleged that staff had bribed government officials, pharmaceutical industry groups, hospitals and doctors to promote sales.