A whistleblower is to face the foreign office at an employment tribunal after he was dismissed for leaking documents to the press.

Derek Pasquill, a London-based employee of the Foreign and Commonwealth Office (FCO), was sacked in 2008 even though an Old Bailey judge dropped six charges under the Official Secrets Act.

The former civil servant, who joined the FCO in 1986, had passed papers to the Observer newspaper and New Statesman magazine in 2005 and 2006 because he was concerned about the government's involvement in what he saw as radical Islamic groups, as well as the FCO's "extraordinary rendition".

Charged with making disclosures that were damaging to international relations, he was acquitted in January 2008 after the court heard minutes of a foreign office discussion which undermined the allegation that the leaks were damaging.

However, the FCO continued disciplinary procedures against him and he was sacked seven months later. Pasquill claims that he has been made a scapegoat, that his leaks were in the public interest and this he was punished unlawfully. He is demanding compensation for loss of earnings and injury to feelings.

A foreign office spokeswoman said: "The FCO strongly denies any allegations that Derek Pasquill was dismissed for making a public interest disclosure. His dismissal from the FCO was as a result of his gross breach of trust and wilful failure to raise his concerns under procedures available to him. He was dismissed under our internal misconduct procedure which is based on best practice."