The Serious Fraud Office (SFO) has kept tight-lipped over whether it is withholding information from Thailand about corruption allegations because of the country’s human rights record.

Authorities in Thailand opened an investigation into engineering giant Rolls-Royce after the company’s £671m deferred prosecution agreement with the SFO. Thailand is reported to be considering introducing the death penalty for corruption cases.

An SFO spokesperson told the Gazette it could not comment on any international assistance. ‘This is a longstanding convention, to protect our investigations and proceedings,’ the spokesperson added.

According to a statement of facts released under the deferred prosecution, Rolls-Royce paid more than $36m between 1991 and 2005 to agents to help it secure contracts to supply aero engines to companies including Thai Airways.

However, local newspapers have reported that the SFO has yet to hand over information to Thailand’s National Anti-Corruption Commission for fear of how the information would be used.

Robert Amaee, a partner at international claimant firm Quinn Emanuel Urquhart & Sullivan, said that agencies have to balance their desire to assist each other with their fundamental obligation to safeguard the human rights of suspects by respecting privacy and due process.

Jonathan Fisher QC, lead counsel at barrister law firm Bright Line Law, said that in any case of cooperation where assistance is being sought from another country the UK will ‘have on its mind’ how the information is going to be used.

Fisher, while not commenting on Thailand directly, said: ‘If you are giving information to an authority whose human rights record is not in line with yours then that obviously presents difficulties.’