A Belgian police officer stands guard outside a school in central Brussels November 25, 2015. REUTERS/Yves Herman

BRUSSELS (Reuters) - Belgian federal police searched a house in a small town south of Brussels on Thursday in what prosecutors told local media was part of investigations into the Islamic State attacks in Paris, adding that no one was detained.

The mayor of Sambreville, Jean-Charles Luperto, also told local media after the operation was over that police had been looking for material evidence rather than suspects.

Federal prosecutors could not be reached for comment.

Brussels remains on high alert after a four-day security lockdown ended on Wednesday. That was prompted by fears of more attacks like the one carried out in Paris on Nov. 13 by French and Belgian militants.

Police are hunting a Brussels man suspected of taking part in the Paris violence, and possible accomplices.

Of five people held in Brussels on terrorism charges, two admit driving Salah Abdeslam, brother of suicide bomber Brahim Abdeslam, back from Paris to Brussels - a six-hour round trip just after the attacks. But they deny any knowledge of the plot.

Two other men are charged with driving Abdeslam around Brussels once he got back. A fifth has not been identified.