Two men, aged 25 and 29, were detained in Halifax, West Yorkshire, in northern England, "on suspicion of the commission, preparation or instigation of acts of terrorism," London's Metropolitan Police said.

The BBC reported that they were thought to be British Pakistanis, being held on suspicion of involvement in facilitating terrorist activities overseas, although police declined to comment.

A further three suspects, two aged 24 and one 32-year-old, were arrested by anti-terror officers who raided four addresses in the city of Manchester, north-west England.

Police from the Met worked with colleagues from West Yorkshire to carry out the Halifax raids at around 6:00 a.m. (0600 GMT).

A Metropolitan Police spokeswoman said the arrests came as part of an "intelligence-led operation" and stressed that the operation was not carried out by armed officers.

The men were arrested at separate houses in Halifax which are now being searched along with two other houses there and a London flat, she added.