The men, three aged 19 and one 24, were detained under counter-terror laws in the Sparkhill area on suspicion of fundraising for terrorist purposes and of travelling to Pakistan to undertake terrorist training.

"Today's arrests were pre-planned and not made in response to any immediate threat to public safety. Officers were unarmed," said a statement from West Midlands Police.

They are the latest arrests in a counter-terror investigation in Britain's second biggest city which was launched in September.

Police say eight people have so far been charged as part of the probe, with seven remanded in custody after appearing in court in London.