Four men have been arrested in Manchester, in an anti-terrorism investigation unrelated to the recent attacks.

LONDON (Reuters) - Anti-terrorism detectives said they arrested four men in Manchester on Wednesday after a tip-off warning of “the existence of a potential threat”.

Three men had been held under the Terrorism Act 2000 and the fourth under immigration laws. All were detained in the Longsight area of the city.

“The arrests have been made following information received by police of alleged terrorist activity and of the existence of a potential threat,” a Greater Manchester Police spokesman said.

No armed officers were involved in the operation, the spokesman said, adding the arrests were not linked to any recent incidents or investigations.