A second man has been detained in an investigation into an alleged plot to attack a church near Paris, French officials said.

The detention occurred today in Saint-Ouen north of Paris, according to a French security official. The man's DNA was found on a hairbrush in the house of Sid Ahmed Ghlam, the chief suspect in the thwarted attack, the official said.

The Paris prosecutor's office confirmed that a suspect is in custody.

Authorities say Ghlam, a computer science student, planned an attack on a church in Villejuif south of Paris and is suspected in the killing of a woman nearby. He was arrested and handed preliminary terrorism-related charges.

It is unclear whether the man detained today was involved in the plot.