Police in Belgium have made 12 arrests in a huge anti-terrorism operation, nearly three months after the deadly bomb attacks on Brussels.

Those detained overnight are suspected of plotting a terrorist attack, prosecutors say. They were among 40 taken in for questioning.

Searches were conducted in 16 municipalities, mainly around Brussels, with checks on 152 lock-up garages.

PM Charles Michel said security would be stepped up at public events.

He tweeted (in French) after a meeting of the Belgian security council to say events would go ahead as planned and he urged the public to remain calm.

According to a report by public broadcaster RTBF (in French), terrorism suspects were seen driving on Friday near a fan zone in central Brussels, where Saturday's Euro 2016 match between Belgium and the Republic of Ireland is due to be relayed from France by giant screen.

On 22 March, bombs killed 32 people at a Brussels airport and a metro station.

Protection for ministers
No arms or explosives were found during the searches, which passed off without incident, Belgium's federal prosecutor said in a statement.

Among the areas where searches took place was Molenbeek, a Brussels district which has become notorious because of its associations with jihadists.

The federal prosecutor said the operation had been launched after investigations which "necessitated an immediate intervention".

The country is under a level 3 terror alert, one below maximum.

"It is not over," Interior Minister Jan Jambon was quoted as saying by Associated Press news agency on Saturday.

"We remain under terror alert three. It means that something is still up. Last night, we had a very successful action."

There were several warnings of further attacks in recent days.
On Friday evening, four federal ministers including Mr Michel were placed under heightened police protection along with their families, Belgian media report.

Belgian police are said to have recently received a warning that a group of militants from the so-called Islamic State (IS) group had left Syria en route for Europe, planning new attacks in Belgium and France.

An unnamed security source was quoted by Belgian newspaper DH (in French) on Wednesday as saying the group had "left Syria about a week-and-a-half ago aiming to reach Europe via Turkey and Greece by boat without passports".
Meanwhile, a Belgian national named as Youssef EA was arrested on Friday and charged on suspicion of terrorist activities in connection with the March attacks, which were claimed by IS.

Belgian media report that he is the eighth person to have been charged over the attacks, which were carried out by three suicide bombers.

Investigators have established connections between the Brussels bombers and the IS attacks on Paris on 13 November, in which 130 people were killed.

Several of the Paris bombers came from Belgium and some of the bombs were made in a flat in Brussels.

>BBC