Turkey has claimed it notified Belgian authorities last summer that one of the Brussels suicide bombers was a "foreign terrorist fighter".

The country's president, Recep Tayyip Erdogan, said Ibrahim El Bakraoui had been detained near the Syrian border in June 2015 and deported to the Netherlands.

He added: "Belgium ignored our warning that this person is a foreign fighter." El Bakraoui was later freed from custody.

It has also emerged that both Ibrahim El Bakraoui and his younger brother Khalid, the man behind the bombing at Maalbeek metro station, were convicted criminals.

Najim Laachraoui, the other Islamic State attacker at Zaventem Airport, was the suspected bomb maker in last November's Paris massacre.

Belgium's terror threat alert remains at its highest level as police pursue a suspect captured on CCTV alongside Ibrahim El Bakraoui and Laachraoui - moments before they detonated their suitcase bombs.

The man, who was dressed in a light-coloured jacket and a hat, is yet to be named by investigators.

Prosecutors have claimed his suitcase bomb, which failed to detonate, was the largest of them all.

Belgian counter-terror officials have raised the prospect that other suspects linked to the attacks may also still be at large.

In total, the attacks have killed at least 31 people - a student and a mother of twins among them.

Local media reports suggest that of the 150 injured victims still in hospital, 61 of them are in intensive care.

Four Britons were among those hurt in the blasts, and worried relatives have said they are "desperately" searching for David Dixon - a man originally from Hartlepool who is feared to have been on Brussels' subway system at the time of the Maalbeek explosion.

The UK's Home Secretary, Theresa May, is meeting her counterparts from EU nations in Brussels later for specially convened talks about the bombings.

An EU statement said the meeting is "intended to show solidarity with Belgium and discuss the actual state of play in the fight against terrorism".

(Sky News)