A convicted radical who killed a French police couple in an Islamic State group-inspired stabbing was carrying a "hit list" of VIPs and urged followers to turn Euro 2016 into a "graveyard", officials said.

Key points: French police will now carry weapons off-duty beyond Paris attacks state of emergency

French police will now carry weapons off-duty beyond Paris attacks state of emergency The "hit list" included police officers, politicians, journalists and artists

The "hit list" included police officers, politicians, journalists and artists Prosecutor says assailant was responding to IS calls to "kill infidels"

Monday's assault in a small town north-west of Paris was the first deadly strike in France since the coordinated attacks in the capital by an Islamic State terror cell in November, which killed 130 people.

Larossi Abballa, who was under surveillance after serving time for links to jihadist networks, stabbed 42-year-old police commander Jean-Baptiste Salvaing outside his home.

He took Salvaing's 36-year-old partner Jessica Schneider — a secretary at a police station in a nearby suburb — and the couple's three-year-old son hostage in the house, and killed Schneider by slitting her throat.

Jessica Schneider and her partner Jean-Baptiste Salvaing. ( AFP: Police Nationale )

Abballa then posted on Facebook a live 13-minute video of himself with the child in which he admitted the murders and urged fellow jihadists to carry out more bloodshed.

The 25-year-old was killed during a police raid which ended the standoff, while the child escaped unharmed but in shock.

In the wake of the attack in Magnanville, police unions said officers would now be able to carry weapons while off-duty beyond a state of emergency that was declared after the November attacks, but which is due to expire next month.

Paris prosecutor Francois Molins said Abballa, who came from the nearby suburb of Mantes-la-Jolie, told police negotiators before his death that he had sworn loyalty to the Islamic State (IS) group three weeks earlier.

He told police he was responding to a call by IS leader Abu Bakr al-Baghdadi to "kill infidels, at home, with their families".

IS claimed Monday's attack in a statement issued by the Amaq news agency, a regular conduit for IS announcements.

France's Prime Minister Manuel Valls called the attack a watershed in terms of horror.

"We're left cold, because a frontier in horror has been crossed, and that is of the home, the intimacy of the family, even, of a couple of civil servants," he said.

"And the weapon against terrorism is liberty and democracy … it is the state of law, and you can count on my determination in that also."

'Turn the Euro into a graveyard'

Mr Molins said police had found a hit list at the scene naming police and VIPs including politicians, journalists, celebrities and rappers to be targeted — they also found three knives, one of them covered in blood.

Three associates of Abballa have been arrested over the attack, Mr Molins said.

One of them was among seven people convicted alongside Abballa in 2013 over their involvement in a network recruiting jihadists for Pakistan, Mr Molins added.

Monday's stabbings comes with France on high alert during the Euro tournament, with up to 90,000 police and security guards deployed to ensure the safety of local and visiting fans.

A police vehicle blocking the road during the assault. ( AFP: Matthieu Alexandre )

In his Facebook video, Abballa called on supporters to attack police, journalists, public figures, prison guards and rappers and to "turn the Euro into a graveyard" — the video was later removed.

Interior Minister Bernard Cazeneuve said Monday's killings showed the gravity of the threat to security forces "who are paying a heavy price to ensure the safety of the French".

Police unions announced they had secured the right for officers to remain armed while off-duty, which has until now only been allowed under the terms of the state of emergency declared in November.

"The minister announced to us that the authorisation to bear arms would be extended beyond the state of emergency," said Yves Lefebvre of the Unite SGP-FO group, after he and other union leaders met Cazeneuve.

The state of emergency is due to run out on July 26.

wires/ABC