GlaxoSmithKline and AstraZeneca, the pharmaceutical groups, have been ordered to release confidential documents to the Serious Fraud Office as part of its investigation into bribes allegedly paid to Saddam Hussein’s former Iraq regime.

The companies, which both deny wrongdoing, were served notice a month ago and have been asked to hand over emails, faxes, contracts and invoices. Eli Lilly, the US pharmaceutical company that operates in the UK, also confirmed it had received a request from the SFO to hand over documents in relation to the same investigation.