LONDON (Reuters) - Five Pakistani men arrested in a British anti-terrorism operation but never charged have been refused bail because they had exchanged a series of coded emails. The five were among 12 men, mostly students, arrested in high profile counter-terrorism raids across northwest England in April but never formally charged with any criminal offence because of insufficient evidence. They are being detained while the government tries to deport them and were refused bail at their hearing last month, the Special Immigration Appeals Commission, which deals with such cases, revealed on Friday. A series of seven emails exchanged between Shoaib Khan, 27, and an associate alleged to be an al-Qaeda operative detailed a 'nikah or wedding which the British Security Service said most likely referred to an intended attack. The emails also included girls names such as 'Nadia which might refer to ingredients used in an explosive device, the ruling said. Khans lawyer said the emails referred to girls, though not by their own names, that Khan hoped to marry in April 2009. Final interpretation of the emails will be addressed at a hearing next year. The five Pakistanis, who will remain in custody until that hearing, have not been linked to anyone arrested with explosives, and no explosives have been found, SIAC said.