Three more people have been detained by French police in connection with a planned terror attack on at least one church near Paris, it emerged on Sunday.

Police believe that the suspects, who have not been identified but are known to be male, may be linked to Sid Ahmed Ghlam, who was arrested last week on suspicion of planning to attack "one or two churches" near the capital.

A French security official confirmed that three men were being detained and questioned by anti-terrorist investigators. The DNA of two of them had been found in Ghlam's apartment; one in the bedroom and another on a hairbrush. The third may have provided logistical support for the alleged plot, the Independent reports.

Ghlan, a 24-year-old Algerian student, was known to security services and had publicly expressed a wish to travel to Syria. He was taken in by police on March 19 after accidentally shooting himself in the leg.

According to French Interior Minister Bernard Cazeneuve, notes "unambiguously demonstrating" that Ghlam was planning an attack were found during a search of his home, and three Kalashnikov assault rifles were seized from his car, along with bulletproof vests.

The Paris chief prosecutor said last week that phones and computers belonging to the suspect suggested that he had been in contact with a French speaker, possibly in Syria, who had encouraged him to carry out an attack on a church. It is not known if Ghlam is directly linked to any terror organisation.

The Algerian is also being investigated in connection with the murder of a 32-year-old woman who was found dead in her car last Sunday, having been shot three times in the head.

Ghlam was charged on Friday with "murder, attempted murder and association with criminals with a view to commit crimes against people".

France is still reeling from Islamist attacks on its capital in January. 17 people died when gunmen attacked the offices of satirical magazine Charlie Hebdo and a Jewish supermarket. According to French prime minister Manuel Valls, the intelligence services have foiled five planned attacks since then.