According to the Belga press agency, the young man was arrested around midday Wednesday in a Brussels hotel following a large-scale search operation. 

In early afternoon, the Brussels public prosecutor's office announced the arrest of an individual in the Belgian capital, without confirming that it was the individual who had been sought.

The terrorist threat level in Belgium was raised last week from two to three, the second-highest level and considered "serious".

This followed an attack in the Belgian capital in which two Swedish nationals were shot dead, and another injured, by a radicalised Tunisian. 

The attacker was shot dead by Belgian police on October 17, the day after the attack.

Adding to the fears is the ongoing war between Israel and Hamas which was prompted by the unprecedented attack by the Palestinian Islamist movement on Israeli territory on October 7, killing more than 1,400 people, mostly civilians. 

More than 220 others were kidnapped amid the attack, according to Israeli officials.

Israel declared a war to "annihilate" Hamas, and has been relentlessly pounding the Gaza Strip.

More than 6,500 Palestinians, mainly civilians, have been killed, according to the latest toll from the Hamas health ministry in Gaza.

Against this backdrop, the threats made on Tuesday by the young Palestinian exile were taken very seriously.

"We can't allow the slightest lapse in our precautions," said the informed source.