Belgium deploys troops following anti-terror raids

Troops have been deployed across Belgium to guard potential targets of terrorist attacks, following a series of anti-terror raids and arrests.

Up to 300 soldiers will be mobilised in Brussels, Antwerp and elsewhere.

Europe is on high alert after Islamist gunmen killed 17 people in Paris. More than 20 people have been arrested in Belgium, France and Germany.

There are increased concerns about the return of young Europeans who have gone to fight in Iraq and Syria.

Uniformed soldiers could be seen outside Jewish schools and government buildings in Belgium on Saturday. 

"Up to 300 troops will be progressively deployed," the Belgian Prime Minister's office said in a statement (in French).

"The mobilised troops will be armed and their primary responsibility will be to survey certain sites," it said, adding that the soldiers could be sent to cities such as Verviers.

Defence ministry officials said 150 police were already in place, a number that they expected to double over the course of the coming week.

The security threat level would remain raised at three - the second highest level - for at least week, they said.