Two of the men who carried out attacks in Brussels on Tuesday have been named by Belgian media as the brothers Khalid and Brahim el-Bakraoui.

The RTBF broadcaster quoted a police source as saying Brahim was a suicide bomber at Zaventem airport. Twin explosions there killed 14 people.

It said Khalid was the suicide bomber at the Maelbeek metro station, where about 20 people died.

Belgium is observing three days of national mourning.

So-called Islamic State (IS) has said it was behind the attacks and warned that more would follow.

A minute's silence for the victims will be held at midday (11:00 GMT).

RTBF said the brothers were known to police and had criminal records.

The broadcaster, quoting the police source, said that Khalid el-Bakraoui, 27, had used a false name to rent the flat in the Forest area of the Belgian capital where police killed a gunman in a shootout last week.

It was during that raid that police found a fingerprint of Salah Abdeslam, the main suspect in the Paris terror attacks of 13 November.

He was arrested in a raid in Brussels last Friday and is due to appear before a pre-trial court on Wednesday.

Khalid el-Bakraoui is on the Interpol website. It says he is being sought for terrorist activities.

RTBF said Khalid was jailed for five years in 2011 for car-jacking while Brahim, 30, was sentenced in October 2010 for firing at police.

Brahim el-Bakraoui is believed to be in the middle of a CCTV image taken at Zaventem airport and released by police.

He and the man on the left were believed to have been killed in the airport attack.

Belgian newspaper La Derniere Heure said that the man wearing the hat is Najim Laachraoui.

It reported on Wednesday that he had been arrested in the city's Anderlecht district, although this has not been confirmed.

Laachraoui was named earlier in the week by police as a wanted accomplice of Abdeslam.

Federal prosecutors have not commented on the latest reports but said they would provide more information on Wednesday.

'Black day'

The airport explosions happened in quick succession shortly after 08:00 local time (07:00 GMT) on Tuesday.

A third bomb was found and destroyed in a controlled detonation.

About an hour later another explosion ripped through a train at the Maelbeek metro station in the Belgian capital, killing about 20 people.

The first of the victims to be named is Peruvian Adelma Tapia Ruiz, 37.

She had been at Zaventem airport with her Belgian husband and twin four-year-old daughters, who were unharmed, her brother told Peruvian radio.

Belgian Prime Minister Charles Michel said Tuesday was "a day of tragedy, a black day".

The country has raised its terrorism alert to the highest level.