Updated | Brussels remains in lockdown as two suspects evade capture

Two suspected terrorists remain at large in Brussels and threaten to commit “very dangerous acts” as the Belgian capital entered its second day with troops continuing to keep the city in lockdown.

Bernard Clerfayt, the mayor of Schaerbeek, one of Brussels’ municipalities, said the area was still facing a grave threat, and that “there are two terrorists in the Brussels region that could commit very dangerous acts.”

Officials said several men were being sought by security authorities amid speculation that a series of cells may be planning attacks in the heart of the EU.

Belgian authorities are searching for Salah Abdeslam, identified as a ringleader of the attacks which killed 130 people in Paris nine days ago. Belgian media have reported sightings of Abdeslam, a 26-year-old Frenchman, in or around Brussels. He has reportedly been in touch with friends on Skype asking for help in getting back to Syria and is believe to be carrying what might be an explosive device.

However Jan Jambon, the interior minister, told reporters that a number of suspects were sought, not just Abdeslam. “There are several suspects, that’s why we have put in place such a concentration of resources. We are following the situation minute by minute. There’s is no point in hiding that there is a real threat, but we are doing everything we can, day and night, to counter this situation,” Jambon said.

People in Brussels have been urged to avoid crowds, while the city’s metro system was closed down on Saturday until the Sunday afternoon. Shops remained closed, football matches were cancelled, concerts were called off, while music venues, museums, and galleries shuttered.

The measures and the deployment of armed forces onto the streets of the Belgian capital came after the Belgian government raised the terror threat alert level to maximum on Friday night, warning of a possibility of terrorist strike involving firearms and explosives. The rest of the country was put on a level three alert, one level short of the maximum.

“Following a new assessment, the terror alert level has been raised to level four, very serious, for the Brussels region,” said a government statement. “Analysis shows a serious and imminent threat that requires taking specific security measures as well as specific recommendations for the public.”

Charles Michel, Belgium's prime minister, moved to increase the state of alert in Brussels to the highest level early on Saturday in response to the threat.

“We’re mobilising very strong security capacities,” said Charles Michel, the prime minister. “There’s a threat of attack by several individuals in several places. The [crisis centre] took this decision following information on a risk of attack similar to Paris.”

Belgium reportedly supplies the most foreign fighters to Syria compared to other EU countries in per capita terms. Many come from Molenbeek, a Brussels borough with a large Muslim community. Jan Jambon, the interior minister and a Flemish nationalist, said that of 130 foreign fighters who were known to have come home from Syria, 85 were living in Molenbeek, which lies just west of the city centre. He demanded that the local authorities conduct a “door-by-door” vetting of who was living in every house and flat in the borough.