Much of Europe was tense and on high alert Sunday as Belgium's justice minister says the alleged mastermind in last week's foiled terror attack remains at large.
Koen Geens told Belgian television that the suspect was not among four people arrested in Greece, where he was believed to have fled.
But Belgian prosecutors still plan to ask Greece to extradite one of those arrested in connection to the thwarted terror strike.
Belgian media have named the wanted mastermind of the plot as Abdelhamid Abaaoud. The 27-year-old Belgian of Moroccan descent is suspected of leading an Islamic extremist cell in the eastern town of Verviers.
Authorities say the cell was about to launch a major terrorist attack on police targets before officers raided their hideout Thursday, killing two in a fierce gunbattle.
Belgium sent military troops into its streets Saturday for the first time in 35 years, in a push to tighten security.
Meanwhile, the two brothers who gunned down 12 people in the Charlie Hebdo massacre in Paris have been buried in secret, unmarked graves in France.
French authorities said that Cherif Kouachi was buried just before midnight Saturday in a cemetery in the Paris suburb of Gennevilliers, even as his family was kept away. The gravesite was not marked so that it does not become "a pilgrimage site" for Islamists.
His older brother, Said, was secretly buried a day earlier in the northeastern city of Reims.
France expedites citizenship for Malian hero
Meanwhile, France says it is granting expedited citizenship to Lassana Bathily, the 24-year-old Muslim from Mali who hid customers in a basement refrigerator before escaping to alert police about the attack on a kosher grocery story in Paris that followed the assault at the Charlie Hebdo offices.
Malian Lassana Bathily, a Muslim employee who helped Jewish shoppers hide in a cold storage room from an islamist gunman during the Jan. 9, 2015 attack, is pictured in Paris, Jan. 15 , 2015.
Bathily told VOA's Bambara service Saturday that French President Francois Hollande called him and promised to give him citizenship.
The grocery store worker said his actions had "nothing to do with faith," adding that the customers were "innocent" people who "had not done anything."
Bathily has been hailed as a hero for his actions during the terrorist attack.
The gunman, Amedy Coulibaly, who identified with Islamist extremists, attacked the store during a three-day terror spree in Paris in which 17 people were killed.
The hero and the gunman were both black French speakers of Malian origin, causing some confusion when Bathily left the store to get help.
He was handcuffed for 90 minutes by police until people who knew him confirmed he was not the attacker. Bathily drew a map of the store for police. After four years of working there and praying within its walls during his shifts, he thoroughly knew the place.
Bathily told VOA "Even if I'm being called a hero, I'm not going to change."
Bathily applied for citizenship in 2014 after living in France for eight years. The Interior Ministry says his paperwork has been expedited and Interior Minister Bernard Cazeneuve will preside over Bathily's naturalization Tuesday.