Six men have been arrested in Birmingham as part of a large intelligence-led counter-terrorism operation, police said.

The men were detained at or near their homes overnight on suspicion of the commission, preparation or instigation of an act of terrorism in the UK.

A spokeswoman for West Midlands Police said the men, aged between 25 and 32, were taken into custody by unarmed officers in the Moseley, Sparkbrook, Sparkhill, Ward End and Balsall Heath areas of Birmingham between 11.30pm on Sunday night and 1am on Monday.

The spokeswoman also confirmed that a 22-year-old woman from Saltley, Birmingham, had been arrested at 6.30am on suspicion of failing to disclose information contrary to the Terrorism Act 2000.

The suspects are being held for questioning at an unnamed police station in the West Midlands Police area, the spokeswoman added, and specialist police teams are now searching their homes and seven other properties in Birmingham.

In a brief statement, West Midlands Police’s Assistant Chief Constable for Security, Marcus Beale, said: “The operation is in its early stages so we are unable to go into detail at this time about the nature of the suspected offences.

“However, I believe it was necessary to take action at this time in order to ensure public safety.”

Although the nature of suspected offences has not been disclosed, the arrests are not believed to have any connection to the Liberal Democrats’ autumn conference, which is currently taking place at Birmingham’s International Convention Centre.

Anyone with information to assist the inquiry, which is being led by the West Midlands Counter Terrorism Unit, is asked to call the confidential anti-terrorist hotline on 0800 789 321.