Close to 14,000 police officers took to the streets of Brussels on Thursday to protest curtailed pension rights, snarling up traffic in the Belgian capital, Belga news agency reported.

The demonstration, organized by trade unionists, kicked off at around 10:30 am (0830 GMT) with around 13,900 participants, according to police figures.

"The cops are fed up. Don't mess with our status," read one banner. "Early retirement: A right! Acknowledge the difficulty of our job," stated another.

At issue is a July constitutional court decision cancelling the right of officers who were once part of the country's paramilitary force to retire earlier than regular police officers, who must work until the age of 62 to draw a full pension.

The decision adds up to eight years to the career of some officers, according to Belga.

Belgium's paramilitary police was integrated into the regular police force in 2001. Thursday's police demonstration was the largest since the 2001 reforms, Belga wrote.