Hollande condemns 'cowardly' terror attack on French police

French President Francois Hollande on Tuesday called the killing of a police officer and his partner by a man claiming allegiance to the Islamic State group a "terrorist act" and warned France still faced a serious threat.

The attack is the first such deadly strike in France since the coordinated attacks on Paris by an IS cell in November in which 130 people were killed.

Hollande said the 42-year-old officer and his partner, who were attacked at their home northwest of Paris overnight, were "murdered in cowardly fashion".

"It's unquestionably a terrorist act," Hollande said, stressing that France, which is currently hosting the Euro 2016 football championships was still "facing a very significant terrorist threat".

Sources close to the investigation identified the suspect, who was killed in a police raid, as Larossi Abballa and said he was convicted in 2013 over his role in an extremist group with links to Pakistan.

The sources later confirmed that the 25-year-old assailant was also part of a more recent investigation into a network recruiting extremists for the fight in Syria.

During failed negotiations with police that ended with elite RAID officers storming the house, the attacker claimed he was also acting on behalf of IS.

He repeatedly stabbed the police officer and then killed his partner, who was found with knife wounds to her neck.

The couple's three-year-old son was found after the police operation, "in shock but unharmed", a prosecutor added.

A Tuesday morning report on Amaq, the Islamic State group's media outlet, said "sources" had confirmed the attacker was acting on behalf of the militant group.

Amaq has recently changed the format of its claims of IS responsibility for attacks, from a direct declaration to an indirect "sources said..." attribution. Analysts suggest this may either be the media outlet's attempt to distance itself from IS, a bid to seem more credible in the West - or that the report has not been sanctioned by IS leaders.