The country’s government announced the change yesterday. Level 3 means "a possible and real threat".
The UK Foreign Office is continuing to warn British tourists to remain “alert and vigilant”.
It added that over-ground trains, including international services, airports, trams and buses are operating.
The Brussels metro network is expected to resume normal service from today, with additional security in place.
“Some public events may be cancelled and some tourist attractions closed. Contact event organisers for information on whether specific events are going ahead”.
Around 1.8 million British tourists visit Belgium every year.
