Khobaib Hussain, Ishaaq Hussain and Shahid Kasam Khan, all 19, and Naweed Mahmood Ali, 24, were charged Friday with engaging in conduct in preparation of terrorist acts contrary to section 5 (1) of the Terrorism Act 2006.

A West Midlands Police spokesman said the charges related to suspicion of fundraising for terror purposes and of travelling to Pakistan for terror training.

"These charges are in connection with Operation Pitsford, a major counter terrorism investigation that has already seen eight people charged and appear in court," he said.

The four men charged Friday are due to appear at Westminster Magistrates' Court in central London.

They were all arrested Tuesday at their homes in the Sparkhill area of Birmingham, Britain's second city.