Three men with links to jihadist Larossi Abballa, who killed a police officer and his partner outside Paris last week, were arrested on Tuesday for carrying out surveillance on other police officers, sources said.
The three were arrested in the Paris suburbs of Mureaux and Mantes-la-Jolie, home of Abballa who was shot dead by police after killing the couple at their home on June 13th.
Police commander Jean-Baptiste Salvaing and his partner Jessica Schneider were killed at their home in nearby Magnanville.
The attacker pledged allegiance to the Islamic State group and, during the assault, streamed a live video on Facebook of himself inside the house with the toddler, urging "other surprises" and pledging to "turn the Euro (2016) into a graveyard".
The investigation has centered on those close to Abballa, with suggestions on Tuesday that the attacker may have had links to the notorious French jihadist Fabien Clain.
Two other men linked to the attacker were charged and detained by an anti-terror court on Saturday.
Saad Rajraji, 27, and Charaf-Din Aberouz, 29, were charged with having links to a terrorist group, but were not found to have any connection to last week's murder.
The two men had been convicted along with Abballa in September 2013 as part of a network to send jihadists to Pakistan, judicial sources close to the investigation said.