An attacker has killed a French police commander and his partner at their home in a Paris suburb before being shot dead by police officers.

The attack on Monday evening was claimed by the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, which said the assailant was one of its fighters.

French President Francois Hollande said on Tuesday that the killing was "unquestionably a terrorist act".

The couple were "murdered in cowardly fashion by a terrorist," Hollande told reporters after the overnight attack at the couple's home northwest of Paris, adding: "France is facing a very significant terrorist threat."

A French Interior Ministry spokesman said the attacker stabbed the officer, Jean-Baptiste Salvaing, outside the home and subsequently barricaded himself inside the building, taking the couple's three-year-old son hostage.

Attempts to negotiate an end to the standoff failed and police forces raided the house in the Magnanville area, killing the suspect, named Larossi Abballa, according to the AFP news agency.

The body of the officer's partner was found inside the house and the boy was rescued.

"Negotiations were unsuccessful, a decision was made to launch an assault," Interior Ministry spokesman Pierre-Henry Brandet said, according to the Reuters news agency.

The Elysee presidential palace said President Francois Hollande was meeting Prime Minister Manuel Valls, Interior Minister Bernard Cazeneuve and Justice Minister Jean-Jacques Urvoas.

Previous conviction

Abballa, who was 25-years-old, had previously been sentenced to a three-year term - six months of which were suspended - for "criminal association with the aim of preparing terrorist acts", in a trial with seven other defendants.

The attacker was linked to armed groups in Pakistan, according to sources close the investigation, the AFP reported.

If confirmed, the attack is the first since ISIL launched bomb and gun attacks across Paris in November last year, killing 130 people.

The French government put into place a state of emergency after those attacks, and ISIL has vowed to continue its campaign in the country.

France like many European countries is dealing with the threat of attacks by fighters from within its own borders returning home after fighting with ISIL and other armed groups in Syria and Iraq.

In March, ISIL fighters killed 32 people in a series of bombings in the Belgian capital Brussels. The men behind the attack were linked to the Paris cell.

The ongoing UEFA European Championship is being held in France and security forces have stepped up security across the country to combat the threat posed ISIL and other armed groups.

Al Jazeera