French police have detained a terror suspect in line with a massive security sweep following the recent murder of a policeman and his wife by a man who pledged allegiance to the Daesh Takfiri terrorist group.

The Versailles prosecutor’s office, which leads the investigation, said on Tuesday that the latest arrest has been part of a deepening probe into last week's attack.

"There was a chance that these people might carry out other attacks against police officers. We were removing any doubt," said the office.

Sources say the investigation is focusing on suspected associates of Larossi Abballa, a 25-year-old Frenchman who stabbed a police commander to death outside his home and killed his wife, who also worked for the police, in Magnanville, a suburb of Paris.

Abballa took the couple's three-year-old son hostage in the June 13 attack. The boy was found unharmed but in a state of shock after police commandos stormed the house and killed the attacker.

France, which is currently hosting the Euro 2016 football event, is on maximum alert.

On June 15, Belgian intelligence sources said that France and Belgium were facing a fresh wave of “imminent” attacks by Daesh terrorists returning from the conflict zones in the Middle East.

French Prime Minister Manuel Valls recently said the intelligence and police services have foiled 15 attacks since 2013 and are waging a non-stop battle to track down would-be terrorists.

On November 13, 2015, terrorists carried out shooting attacks and bombings in the French capital, Paris, killing 130 people.

The Western and European governments were repeatedly warned of a Takfiri backlash when they began supporting militants in their bid to topple the Syrian government.

Those threats have come to pass as attackers linked to Daesh and other Takfiri groups have targeted several countries across Europe.

The International Center for Counter-Terrorism, based in The Hague, said in a report in early April that Belgium, Britain, France and Germany contributed to the militancy in Iraq and Syria by having over 2,830 of their nationals traveling to those countries to join terror groups.

That is more than half of a total of 4,294 foreign fighters who have left the EU member states for those two Arab countries over the past few years.

Western officials estimate that several hundred of the disillusioned extremists have so far returned to their European home countries.

Estimates suggest that some 30,000 foreign fighters from about 104 countries were fighting in Iraq and Syria between September 2014 and September 2015.