British police arrested a terrorism suspect Thursday night in Birmingham, the second largest city of Britain, bringing the total number of arrested suspects to eight in the latest counter-terrorism operation.

West Midlands Police announced in a brief statement that the 20-year-old man was detained on suspicions of the commission, preparation or instigation of an act of terrorism in the country.

He was arrested at a police station, the statement said.

The six men arrested earlier in the week were still in custody and questioned by police officers, while a woman also detained in connection to this operation has been given police bail pending further enquires.

The terrorism threat level in England, Wales and Scotland remains unchanged at "substantial", meaning that a terrorist attack is a "strong possibility."