BRUSSELS — Belgium’s capital will stay at its highest security threat level until at least next Monday over fears of an imminent terror attack, authorities said, as the United States issued a worldwide travel alert for its citizens.

Authorities in Belgium and France were still hunting for Belgian-born Salah Abdeslam, a key suspect in the Paris attacks on Nov 13, when gunmen and suicide bombers killed at least 130 people.

French police yesterday were analysing a suspected suicide belt similar to those used in the Paris assault, said sources close to the investigation.

Authorities found the object, which lacked a detonator, in a dustbin in the southern Parisian suburb of Montrouge. Telephone data placed Abdeslam in the area on the night of Nov 13.

Another police source said the belt appeared to have “the same configuration” as those used by the jihadists.

Fearing a similar attack, Belgium maintained an unprecedented security lockdown in Europe’s capital Brussels, with Prime Minister Charles Michel warning that the threat “remains serious and imminent”, though schools and the Metro will reopen today.

The security measures include the patrols of armed soldiers and police citywide, something a counterterrorism expert says has not been seen in at least two decades.

Meanwhile the federal prosecutor’s office announced that a man who was arrested during a large police operation in Belgium late last Sunday has been charged with involvement in the Paris attacks, the fourth so far.

Mohammed Amri, 27, and Hamza Attou, 20, were charged on Monday on suspicion of helping Abdeslam escape to Brussels after the attacks, while a third unnamed person faces charges of aiding him when he reached the city.

Abdeslam’s brother Mohamed on Sunday told Belgian television he thought Salah had decided at the very last moment not to go through with his attack mission.

Underlining heightened global fears of attacks after Islamists killed scores in Mali, Turkey, Lebanon and Nigeria in recent weeks, the United States issued a worldwide travel alert warning US citizens of “increased terrorist threats”. “Current information suggests that ISIL (another acronym for Islamic State), Al Qaeda, Boko Haram and other terrorist groups continue to plan terrorist attacks in multiple regions,” said a State Department travel advisory.

In Brussels, an eerie atmosphere hung over the city with soldiers in camouflage patrolling everywhere, from railway stations to EU institutions. In the normally bustling historic Grand Place, a few bars and restaurants were open for business but they were struggling to find customers.

In downtown Brussels, the only real activity was that of deliverymen offloading crates for near-empty shops, as builders hammered together stalls for a Christmas market meant to open on Friday.

“My grandson said we should up sticks and move to the south of the Yser river, just like in World War I (after the Germans invaded),” said Michel, a retired man from a Dutch-speaking suburb. “We have to be careful, but life has to go on. Otherwise, we’re finished,” said his wife Patricia. AGENCIES