Authorities in Belgium and France were hunting for Belgian-born Salah Abdeslam, a key suspect in the Paris attacks on November 13, when gunmen and suicide bombers killed at least 130 people.
French police were today analysing a suspected suicide belt similar to those used in the Paris assault, according to sources close to the investigation.
Authorities found the object -- which lacked a detonator -- in a dustbin in the southern suburb of Montrouge. Telephone data placed Abdeslam in the area on the night of November 13.
Fearing a similar attack, Belgium maintained an unprecedented security lockdown in Europe's capital Brussels, with Prime Minister Charles Michel warning yesterday that the threat "remains serious and imminent".
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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 deliverymen offloading crates for near-empty shops as builders hammered together stalls for a Christmas market meant to open on Friday.
"We have to be careful, but life has to go on -- otherwise we're finished," said his wife Patricia.
The army and armed police will remain on the streets in coming days, the Belgian prime minister said, but schools and the metro system would reopen from tomorrow.