Brussels, Nov 21 (IANS): The alert level of the terrorist threat was raised to the highest level in Brussels, Belgium Prime Minister Charles Michel said on Saturday.

This is the first time in Belgium that the terrorist threat alert was raised to level four for a region, the television channel RTBF reported.

It means that the threat is "serious and imminent", Xinhua quoted the media as saying.

According to the Coordinating Body for Threat Analysis (OCAM) of Belgium, it is a threat "that requires taking specific security measures and recommendations for the population."

The OCAM proposed that people in the capital avoid crowded places, facilitate and enforce security checks and do not broadcast rumours.

The OCAM of Belgium last Tuesday raised the terror alert level to level three for the entire country following numerous arrests in Brussels as part of the investigation into the Paris attacks that left over 129 people dead and many others injured.

Level three, a threat "possible and probable", continues to apply to the rest of the country, it added.