BRUSSELS (AFP) -- Belgians observed a minute of silence at 1100 GMT on Wednesday in memory of the victims of the Brussels airport and metro bombings, the country's worst-ever terror attacks.

Defiant applause broke out after the symbolic display of solidarity from a large crowd at the central Place de la Bourse, where mourners have been holding a vigil since Tuesday evening following the attacks that left around 30 people dead.

The mood was sombre at the headquarters of the European Union where Belgium's King Philippe and his wife joined officials led by European Commission President Jean-Claude Juncker.

French Prime Minister Manuel Valls stood alongside the king and leading EU officials who joined Belgian Prime Minister Charles Michel to remember the dead.

On the Place de la Bourse, crammed with people and decked out with flags and flowers left by mourners, the crowd chanted: "Long live Belgium", followed by "Brussels above all".

"We are showing our compassion," said Brussels mayor Yvan Mayeur. "We need to reach out today to all those who were hurt."