Belgian federal prosecutor's office said Monday that it has decided to release Faycal C, the 'man in the hat' seen on CCTV footage next to two suspected suicide bombers before the deadly blast that rocked Brussels Airport, due to lack of evidence.

Belgium's federal prosecutor's office said it had freed a man it had named only as Faycal C., adding it had no evidence to justify holding him. He had been charged on Saturday with "terrorist murder".

Belgian media had identified the man as Faycal Cheffou and a source close to the investigation had said officials believed he was the man in the footage.

Earlier on Monday, police had issued an appeal for witnesses, saying they were seeking to identify the man caught on CCTV with two others thought to have blown themselves up. Police say the third man appeared to have left his bomb, which failed to explode, and fled.Faycal C, the man in a light jacket seen pushing a trolley with a suitcase on it in the airport video footage, which was released on Monday along with the appeal, has been dubbed "the man in the hat".

Cheffou, a self-styled freelance journalist, had been charged with attempted and actual terrorist murder, according to a source close to the investigation, speaking on condition of anonymity.

But the source repeated that there had been no official identification, implying police may be having difficulties linking him to the figure captured on CCTV, who was wearing glasses and whose hat was pulled down over his face.

The official police notice said they were seeking to formally identify the man, who is suspected of dumping his case containing a bomb, which did not go off, before running from the terminal.

Half a dozen people have been charged in Belgium following Tuesday's attacks on the airport and the metro. The death toll rose to 35 on Monday, excluding the two airport bombers and a third who blew himself up on a rush-hour train.

A Europe-wide hunt for suspects has revealed links with the network that attacked Paris last year and also foiled a new potential attack on France last week, officials said. But several suspects are reported to be still at large.

SUSPECTS AT LARGE

Daesh has claimed responsibility for both the Paris attacks and those in Brussels, which exposed weaknesses within intelligence services in Belgium, where some of the Paris attackers lived, as well as insufficient cooperation between security services across Europe.

Dutch anti-terrorism police arrested a 32-year-old suspect on Sunday in Rotterdam on France's request and Italy arrested an Algerian on Saturday suspected of having forged documents for militants linked to the Brussels and Paris attacks.

Germany has also conducted raids but its Federal Criminal Police Office was among European security agencies still hunting for at least eight mostly French or Belgian suspects on the run in Syria or Europe, Die Welt am Sonntag newspaper said.

The U.S. State Department confirmed four U.S. citizens were among victims of nine different nationalities, including Belgian. More than 300 people were injured, many of them seriously.

Belgian Health Minister Maggie De Block said more of those wounded in the attacks had since died. "Four patients died in hospital. Medical teams did everything possible. Total victims: 35," she said in a tweet.

Other foreigners killed were British, Chinese, Dutch, French, German, Italian and Swedish.

The airport in Brussels remained closed on Monday and the metro was running a reduced service in the capital which was largely shuttered for the Easter holiday.

There was no sign of the nationalist protesters who clashed with police on Sunday at the Brussels bourse, where mourners have gathered and placed candles, wreaths and messages for victims.

The State Department has declined to name any of the four U.S. citizens killed, citing respect for their families.

Two of them were identified by relatives as Justin and Stephanie Shults, residents of Belgium originally from Tennessee and Kentucky who were last seen dropping off her mother at the Brussels airport before the explosion in the check-in area.

"The world lost two amazing people," Justin Shults' brother, Levi Sutton, said in a post on Twitter.

"It's not fair."One week after the devastating attacks, which severely damaged Brussels Airport's departure area, the facility is planning to test its capacity to partially resume passenger service.Florence Muls, an airport communications manager, said 800 staff members on Tuesday will test temporary infrastructure and new arrangements designed to handle passenger check-ins.It's too early to say when airport service might actually resume, she said, adding that government and firefighters must approve the new system before Brussels Airport can start handling passenger traffic again.Before the bombings, Brussels Airport served some 600 flights a day and 23.5 million passengers per year.