Two explosions at Brussels airport, several injured:

BRUSSELS: Two explosions were heard at Brussels airport early on Tuesday morning and Belgian media said several people were injured.

The cause of the explosions was not immediately clear.

Sky news in London said the blasts had occurred in the departures lounge and cited reports it had occurred near the American Airlines desk.

Belgian media said rail traffic to the airport was suspended.

The blasts occurred four days after the arrest in Brussels of a suspected participant in November militant attacks in Paris that killed 130 people.

Belgian police had been on alert for any reprisal action.

Social media showed pictures of smoke rising from the departure hall where all windows had been shattered by the blast.

Passengers were seen running away down a slipway from the departure lounge.

Sky News television´s Alex Rossi, at the scene, said he heard two "very, very loud explosions".

"I could feel the building move. There was also dust and smoke as well.

I went towards where the explosion came from and there were people coming out looking very dazed and shocked.

""The thinking here is that it is some kind of terrorist attack - that hasn´t been verified by any of the authorities here at the airport."

There was no immediate official comment on the cause of the attack.