Security has been increased at London Gatwick airport following the explosions in Brussels, an airport spokesman said.

The explosion at Maalbeek station, near the EU institutions in Brussels, at 09:11 (08:11 GMT) this morning has prompted a shutdown of the entire metro system, and trams and buses are not running either. 

A French student has tweeted video of people being moved away from Maalbeek station along the metro track.

Nils Liedtke, who was in the airport when the explosions took place, described the scene to the BBC's Today programme.

Brussels airport has been shut down at Zaventem outside the capital, and the city's bus, tram and metro systems are all closed. 

Eurostar says its services are still running.

David Cameron tweets to say he will chair a meeting of the government's emergency committee this morning.

Brussels airport has tweeted an emergency contact number for those worried about friends or relatives.

French broadcaster TV5Monde has shared another number.

• There were two explosions at around 08:00 (07:00 GMT) at Zaventem airport as people queued to check in
• Belgian broadcaster VRT says at least 13 people were killed and 35 were wounded at the airport
• Shots were heard before the explosions, which appear to have struck near the American Airlines and Brussels Airline check in desk
• Some time later there was also a blast at Maalbeek metro station, very close to the city's main European Union buildings
• The Belgian government has raised the terror alert level to 4 across the country, the highest level

At least 13 people were killed and 35 wounded at Brussels airport, according to Belgian broadcaster VRT.

Owen Li was in the departure area when the bombs went off. 

Mr Li, a financial services worker who lives in Brussels, told the BBC:

"I was eating my breakfast post-security and then suddenly everyone was running towards us. 

"People didn't know what to do, we thought it was just an exercise. 

"Some still stayed at the restaurant but slowly people realised it was real. Staff are trying to find a way to get us out."

Passengers have been taken off trains in the tunnel just outside Schuman metro station.

Evan Lamos has shared some images.

Live pictures from Belgian TV show the crowds outside Zaventem airport, more than 90 minutes after the explosion. 

Image source, VRT

Two bomb packages went off in the departure hall of Brussels airport, Het Laatste Nieuws reports. 

One was close to the SN Brussels Airlines desk and another near the American Airlines desk, it says.

Belgian broadcaster RTBF, citing a hospital source, says up to 10 people died and 30 were wounded in the Brussels airport explosions. 

Police have yet to release an official death toll.

The Brussels metro has tweeted to say the entire system is shut down following reports of a blast at Maelbeek station, close to the city's EU institutions. 

Unconfirmed reports are emerging of an explosion at Maelbeek metro station in Brussels, close to the city's EU institutions. 

Images posted to social media appear to show smoke emerging from the front of the station.

Belgian PM Charles Michel tweets: "The federal government is following the situation closely. Absolute priority goes to the victims and to the aid effort at the airport"  

Belgium has raised its terror threat to the highest level, AFP reports. 

That takes the level for the entire country up from level three to four, the maximum.

The country was already on high alert after a shootout in the Brussels suburb of Molenbeek last week in which Paris attacks suspect Salah Abdeslam was captured.