Swedish man injured in deadly Brussels blasts

"We have information about a Swedish man, but his injuries are not believed to be serious. We are keeping in touch with his family," foreign ministry spokesperson Johan Tegel said.

He told The Local the ministry had no information about any other Swedes involved in the attack.

The injured man, who the Expressen tabloid reported is in his fifties, is understood to have received a minor shrapnel wound in one of the explosions at Brussels airport on Tuesday morning.

Meanwhile, Swedish officers were placed on alert and additional patrols ordered for airports and other undisclosed locations in Sweden.

"Following the explosions in Brussels, police presence is being strengthened at Swedish airports and safety and security building measures increased," said the national police in a statement.

It added it was cooperating closely with Swedavia, which operates airports in Sweden; the national security police Säpo, civil contingencies agency MSB and the foreign ministry.

The attacks in the Belgian capital come three weeks after Sweden lowered its national terror threat level back down to three on a five-point scale, after raising it to a record four ('high') in November.

Säpo said it was keeping a close eye on developments in Belgium, but added on Twitter that Sweden's terror alert would for now remain at a steady level-three ('elevated').

READ ALSO: 'Sweden is mourning with Brussels'

A metro carriage being evacuated. Photo: Evan Lamos via AP

The Brussels airport was hit by two explosions shortly after 8am, then at around 9.20am there was another explosion at the Maelbeek metro station in the city, which is located about 500 metres from EU buildings, and reports of another underground blast nearby.

Later in the afternoon Brussels transport authorities said that at least 20 people died in the attack at Maelbeek, while the country's health minister said 14 were killed at the airport. Almost 200 were believed to have been injured and officials warned the death toll could rise.

The Belgian prosecutor said that at least one of the airport explosions was a suicide bombing, confirming the fears that the capital was targeted by terrorists. Radical group Isis later claimed responsibility, as Belgian police released an airport surveillance camera photo of a man potentially linked to the attack.

They said they wanted to question the man dressed in white on the right.

Swedes in Brussels were urged to contact the Swedish Embassy in Belgium.

"Our main goal right now is to make sure that there are no Swedes among the victims," said interior minister Anders Ygeman at a press conference on Tuesday morning.

A security guard at Stockholm's Bromma airport on Tuesday. Photo: Johan Nilsson/TT

The blasts come just days after the arrest in the city of Salah Absdeslam – the chief suspect from the Paris terror attacks who had been on the run for four months.

Sweden's Prime Minister Stefan Löfven described the explosions as an attack against European democracy.