At a security conference in Brussels Reynders said Abdeslam's apparent claim "may be the reality."
Reynders added that investigators have "found a lot of weapons" and "have seen a new network of people around him [Abdeslam] in Brussels."
"We have found more than 30 people involved in the terrorist attacks in Paris, but we are sure that there are others," Reynders said.
Abdeslam, who was captured in Molenbeek, Brussels, Friday after five months on the run, allegedly told investigators earlier that he planned to commit a suicide bombing at France's main stadium in the Nov. 13 attacks, but then "backtracked" and abandoned his explosive belt, Paris prosecutor Francois Molins said Saturday.
"His first declarations are to be taken with caution and leave open a series of questions that Salah Abdeslam will have to explain," Molins said Saturday.
Abdeslam plans to fight an extradition to France, his lawyer Sven Mary told reporters Saturday.
Molins said Saturday, "This refusal will ... only lead to a longer procedure."
French and Belgian prosecutors were working on another legal exchange different from an extradition, that would enable Belgium to give the suspect to France without government interference.
French officials said they expect Abdeslam to be transferred to France within 60 to 90 days.
The Belgian federal prosecutor has charged Abdeslam with participation in terrorist murder and participation in the activities of a terrorist organization.
He is being held in the maximum-security area of the Bruges prison, a spokeswoman for the Belgian prison administration told ABC News.
Mary told reporters Saturday Abdeslam was "collaborating with the Belgian justice."