A police officer stands guard in front of the London Stock Exchange, October 17, 2011.

Story highlights

NEW: The guilty pleas follow "the largest counter terrorism operation of 2010," police say

The plot involved setting off a bomb at the London Stock Exchange

A total of nine men have pleaded guilty to terror charges, a senior counter terror police officer says

London CNN  — 

At least four men have admitted to “an al Qaeda-inspired plot” to bomb the London Stock Exchange, British authorities said Wednesday

The suspects – Abdul Malik Miah, Gurukanth Desai, Shah Mohammed Lutfar Rahman and Mohammed Moksudur Rahman Chowdhury – pleaded guilty in court, the Woolwich Crown Court said in a statement.

Five other men have also pleaded guilty to terror offenses. Some of them entered their pleas Tuesday, according to the court.

Deputy Assistant Commissioner Stuart Osborne, senior national coordinator for counter terrorism, said he welcomed the guilty pleas by the nine defendants, “following what was the largest counter terrorism operation of 2010.”

The investigation, which was coordinated by the West Midlands Counter Terrorism Unit, also involved police forces in London, Wales and Staffordshire, and national counter terror and security services, he said.

“Our priority is and always will be the protection of the public,” he added.