Belgium raised the alert status for its capital Brussels to the highest level today, shut the metro and warned the public to avoid crowds because of a "serious and imminent" threat of an attack.
A week after the Paris attacks carried out by Islamic State militants, one suspect from Brussels had not been nabbed as yet.
According to authorities, the suspect was highly dangerous. The city was placed on the top Level 4 in the government's threat scale following a meeting of top ministers, police and security services.
"The advice for the population is to avoid places where a lot of people come together like shopping centres, concerts, events or public transport stations wherever possible," a spokesman for the government's crisis centre said.
Belgian prime minister Charles Michel declining to give the reason why the alert level had been raised, told a news conference the government would review the security situation tomorrow afternoon.
Until then, in line with the recommendation of the crisis centre, the metro system would remain closed, he added.
According to the crisis centre website it was calling on local authorities to cancel large events, urging people to avoid crowds, postpone soccer matches and close the Brussels metro for the weekend. It was also stepping up the military and police presence.
According to the television channel RTBF, this was the first time in Belgium that the terrorist threat alert was raised to Level 4 for a region.
It meant that the threat was ''serious and imminent'', Xinhua quoted the media as saying.
The Coordinating Body for Threat Analysis (OCAM) of Belgium, said it was a threat ''that requires taking specific security measures and recommendations for the population.''
The OCAM has called on the people in the capital avoid crowded places, facilitate and enforce security checks and do not circulate rumours.
The OCAM of Belgium last Tuesday raised the terror alert level to Level 3 for the entire country, after numerous arrests in Brussels as part of the investigation into the Paris attacks.
The rest of the country, continues to be under Lever 3, a threat, ''possible and probable''.