Laurent Cipriani, Associated Press
Apolin Pepiezep, lawyer of Mehdi Nemmouche, the Frenchman suspected in the shooting deaths of three people at the Brussels Jewish Museum, speaks with journalists in front of the Appeal Court of Versailles, outside Paris, France, Thursday, June 5, 2014. In court, Nemmouche said he didn't consent to the extradition based on a European arrest warrant.

VERSAILLES, France — A Frenchman suspected of killing three people at the Brussels Jewish Museum is formally opposing extradition to Belgium.

Masked, armed police special forces guarded Mehdi Nemmouche as he appeared in a Versailles court Thursday. The 29-year-old, whose lawyer says he fought with Islamic extremists in Syria, was arrested last week in the probe into the May 24 killings.

In court, Nemmouche was asked whether he consents to extradition based on a European arrest warrant. Calm and unfazed by the proceedings, he responded, "No."

The refusal was likely to prolong the process as authorities explore options. Thursday's proceedings were quickly adjourned until June 12 so that Nemmouche's lawyer could prepare further arguments.

"'We are ready to use every recourse," lawyer Apolin Pepiezep said afterward.

He says there's no proof that his client was the shooter, and argues that he should be tried in France because he is a French citizen and French authorities are equally competent.

Nemmouche, who was born in northern France, also has Algerian citizenship.

He was arrested Friday at a Marseille bus station, armed with weapons that appear to be like those used in the shootings. In a single minute of furious gunfire, three people were killed and a fourth seriously injured in an attack that rocked Jewish communities around Europe.

Nemmouche spent a total of seven years in prison for theft and other crimes, and French judicial officials say he adopted radical Islamic beliefs in prison. He spent about a year in Syria, apparently with the notorious fighting group Islamic State of Iraq and the Levant.