Italian police have arrested an Algerian suspected of making documents for militants linked to the Brussels bombings and Belgian authorities charged a man connected with a French raid as the investigation into the attacks spread to other countries.
With links to the Paris attacks in November becoming clearer, and amid criticism that European countries have not done enough to share intelligence on suspected Islamist militants, co-operation appeared to be deepening.
The suicide bomb attacks targeting Brussels airport and a rush-hour metro train on Tuesday killed at least 31 people, including three of the attackers, and injured hundreds more. Islamic State has claimed responsibility.
Belgian press agency Belga said on Sunday prosecutors charged the man in connection with a raid in Paris on Thursday that authorities say foiled an apparent attack plot.
Belga named him as Abderamane A. who prosecutors had said on Saturday was being held after being shot during a raid in the Brussels district of Schaerbeek. The prosecutor's office could not immediately be reached for comment.
In southern Italy, Algerian Djamal Eddine Ouali, 40, was arrested by DIGOS anti-terrorism police after a series of raids and arrests in Belgium and Germany since the attacks, Italian media said on Saturday.
He was suspected of having made false documents for militants connected to the attacks, Sky TG 24 television and other media said. His name was found in documents in a raid in an apartment near Brussels last October, including some with photos of militants involved in the attacks in Paris and in Brussels and the aliases they used.
Belgian prosecutors also charged three men on Saturday including Faycal C., whom Belgian media identified as Faycal Cheffou and said he was "the man in the hat", as he has become known, in last Tuesday's airport CCTV footage that showed three men pushing baggage trolleys bearing luggage.
However, investigators have still not fully confirmed that Cheffou is that man, a person close to the investigation told Reuters.
The two others in the picture are believed to have blown themselves up.
Cheffou was charged with taking part in the activities of a terrorist group, and actual and attempted terrorist murder.
The other two charged on Saturday, Aboubakar A. and Rabah N., were accused of terrorist activities and membership of a terrorist group. Rabah N. was also wanted in connection with the raid in France.
Brussels mayor Yvan Mayeur told Le Soir newspaper that Cheffou had been detained a number of times at a park where he sought to encourage asylum seekers to turn to militancy.
Organisers called off Sunday's Belgian solidarity march after officials including the city's mayor urged people to stay away in order to spare the over-taxed police force amid fears of another attack.
Officials said 24 victims from nine different nationalities had been identified so far from the attacks in Brussels, where the European Union and NATO are headquartered. Fourteen were identified at the airport and 10 on the metro. A further four people remain unidentified.
In addition, 340 people were wounded, according to the latest official toll, of whom 101 are still in hospital, 62 of them in intensive care, many with severe burns.