<br/> A civil servant was arrested on suspicion of leaking highly sensitive diplomatic cables written by Britain's former US ambassador. Counter-terrorism officers detained the man, who is understood to work at the Department for International Trade, on suspicion of breaching the Official Secrets Act and misconduct in public office. When the documents were leaked last year they caused Britain deep diplomatic embarrassment because they showed Washington ambassador Sir Kim Darroch describing US President Donald Trump as insecure, incompetent and inept. Mr Darroch also suggested that Mr Trump's career could end in disgrace. There were subsequent stories that claimed Mr Darroch said Mr Trump abandoned the Iran nuclear deal to spite his predecessor Barack Obama. In response to the international headlines caused by the leaked cables, Mr Trump tcalled the British ambassador a "pompous fool" and a "stupid guy". Mr Darroch, who has since been made a lord, resigned after US Prime Minister Boris Johnson refused to back him during a televised Tory leadership debate. The arrested civil servant was reported to have been released on bail after being held at a London police station for more than 30 hours. Officers are understood to have seized a laptop computer and his passport from his Westminster apartment. The official is understood to have been suspended on full pay while the Department of International Trade conducts an inquiry. Counter-terrorism police were involved in the investigation after the Crown Prosecution Service concluded that there might have been a breach of the Official Secrets Act. Reports suggested UK government intelligence agency GCHQ also helped with the investigation. The cables did not reveal state secrets but they are likely to have been written on documents titled "secret".