BRUSSELS (REUTERS) - The first details about the man shot dead as he tried to bomb Brussels' Central Station highlight the shadowy new challenge to security services across Europe - the lone-wolf militant.

The 36-year-old Moroccan who part-detonated a suitcase packed with nails and gas bottles on Tuesday appeared to have acted alone, was virtually unknown in his home area and had never been identified by police as a threat.

From Nice to London, men acting alone with guns, knives or trucks have carried out deadly assaults following calls by Islamic State for followers to attack in their home countries, rather than fight in Syria and Iraq as it loses ground there.

Belgian authorities have identified the Brussels attacker only as OZ.

A Belgian security source told Reuters he was Oussama Zariouh.

In an overnight raid, investigators found in his home bomb-making materials similar to the chemicals used in the attacks by Islamic State in Iraq and Syria (ISIS) on Brussels airport and metro that killed 32 people last year.

Zariouh had lived in the poor Brussels borough of Molenbeek since 2013. But unlike the militants who helped plan the 2015 Paris attacks and who also lived there, Zariouh was largely unheard of, according to interviews with residents.

"Oussama is not an uncommon name, so I've heard the name, but here, in this area, no I don't know him," said a Belgian-Moroccan woman called Jamila who lived near Zariouh's home, echoing the sentiment of other residents.

According to Molenbeek Mayor Francoise Schepmans, Zariouh had been investigated only for a minor drug offence.

A Facebook account with his name and matching details said he had graduated from a Moroccan university in 2002 and was self-employed. His postings showed no obviously radical comments or militant links and attracted very few responses.

'DO IT ON YOUR OWN'

The account, not updated for a year, showed many shots of Zariouh, clean-shaven or with a thin beard, apparently alone at the wheel of a car.

"The fact that police couldn't find him in their databases is a bit of a shock, given that lots of searches and raids have been made since the Paris attacks in Molenbeek," said Bruno Struys, a Belgian author who writes on Islamist fighters.

So far, no group has claimed responsibility for the abortive Tuesday attack. Kenneth Lasoen, a security and intelligence expert at the University of Ghent, said its clumsiness showed a lack of operational support.

"This looks like the work of a lone wolf," Lasoen said. "He did not know what he was doing. If this had been Daesh (ISIS), he would have had better instructions about how to do this awful act."

After Zariouh part-detonated his suitcase bomb, he ran downstairs to the station platforms, then ran back up to the concourse and towards a soldier on a routine patrol, shouting"Allahu akbar" - God is greatest, in Arabic.

The soldier shot him several times.

Zariouh's isolation may reflect militants' greater need for secrecy as Europe's security forces step up their surveillance, after years of under-funding of spy services and squabbling among governments.

"Because of the heightened security, if militants want to be successful in a planning an attack, they cannot make their intentions clear to anyone, because at some point that will be picked up by the intelligence services," Lasoen said.

"Daesh is saying: as much as you can, do it on your own," he said.