French interior minister says decided to deploy 1,600 additional police officers at borders and on transport.
Reinforced security also reported in the UK
The Foreign office has set up a helpline
Belgium is sending 225 extra troops to Brussels
Latest reports saying that 15 people killed in the metro blast, that's according to public broadcaster RTBF. It also reported 55 people wounded.
At press conference, Belgium's prosecutor Frederic Van Leeuw gives figure of 21 dead.
Press conference: Belgian PM says no information on whether the attacks are linked to the arrest of Salah Abdeslam last week
AFP - The president of the Front National, Marine le Pen, "is offering her support to the people of Belgium" and calls for the "immediate closure" of borders between France and Belgium.
French PM Manuel Valls has reiterated his "We are at war" announcement that followed the Paris attacks, expressing "solidarity" and "compassion" for the victims of the Brussels attacks (source AFP)
Supporters of Islamic State praised on social media blasts in Brussels that killed about 20 people on Tuesday (source Reuters)
Fifteen people have been killed and 55 injured in a blast on a Brussels metro in Maelbeek, according to public transport operator STIB.