London: British Prime Minister David Cameron today expressed "shock" and promised every possible help to Belgium after a string of explosions ripped through Brussels airport and a city metro station, killing at least 21 people and prompting a high-security alert across European nations.
"I am shocked and concerned by the events in Brussels," Cameron posted on Twitter shortly after the news broke.
"We will do everything we can to help."
The prime minister added he will be chairing a COBRA meeting, held to discuss emergency situations and bring together cohesive government response, later in the day.
"I will be chairing a COBRA meeting on the events in Brussels later this morning," Cameron said.
Meanwhile, security was beefed up across major airports in Europe including London's Gatwick airport as fear of another imminent terror attack remains very strong.
"As a result of the terrible incidents in Brussels, we have increased our security presence and patrols around the airport," the Gatwick airport said in a statement.
Earlier in the day, a string of explosions rocked Brussels Zaventem international airport and a city metro station, killing at least 21 people, according to local media reports.
Police said the attacks were caused by suicide bombers.
The blast at the Maalbek metro station occurred in the close vicinity of the European Union institutions and killed 10 people and wounded 55 others. Brussels has both NATO as well as European Union (EU) headquarters.
The terror strike is widely seen as a revenge attack for the arrest of Paris terror attacks prime suspect, Salah Abdeslam, who was arrested in the Belgian capital last Friday, four months after France's deadliest terror attack in November, claimed by the Islamic State, that killed 130 people.
Cameron himself has spent much time in Brussels recently, in and out of EU summits to renegotiate Britain's membership of the bloc.