BRUSSELS — Responding to rising threats across Europe, France on Thursday sought to extend a sweeping state of emergency for three months, as Belgium proposed tough new measures to detain and monitor suspects who support jihadist groups.

The calls for a crackdown came as French prosecutors confirmed Thursday that the accused ringleader of the Nov. 13 terrorist attacks in Paris was killed in a massive pre-dawn police raid Wednesday. The death of Abdelhamid Abaaoud, a Belgian militant of Moroccan descent, did little to calm European unease about the specter of more attacks.

In Italy, officials said the FBI had warned of a specific threat in Vatican City, Rome and Milan.

In an ominous address – echoing the debate in the U.S. Congress after the Sept. 11, 2001, attacks – French Prime Minister Manuel Valls said authorities must imagine that the grimmest threats are possible.

“We know and bear in mind that there is also a risk of chemical or biological weapons,” Valls told parliament during debate on extending the country’s state of emergency. The temporary measure was enacted immediately following Friday’s deadly multi-pronged attacks on Paris that killed at least 129 people and wounded more than 350.

French Interior Minister Bernard Cazeneuve warned that now “it is necessary to move fast and hard.”

He said that “all Europe must work together to defeat terrorism” and called for an emergency meeting of the continent’s interior ministers on Friday.

Some European leaders seemed prepared to sweep aside cherished traditions that protect rights to privacy and civil liberties.

In Belgium, Prime Minister Charles Michel pressed parliament to pass tough new measures to imprison citizens returning home from fighting in Syria and to broaden law enforcement’s ability to tap phones and detain suspects for three days without charges. He called for shutting down websites that advocate jihad, or Islamic holy war.

The moves came as fears ratcheted up across Europe of more hidden terror cells preparing similar strikes.

Italian Foreign Minister Paolo Gentiloni said Italian security forces were “working to identify five people” who may be planning attacks on St. Peter’s Basilica in Vatican City, Milan’s Duomo or the La Scala opera house.

The U.S. State Department issued a travel warning to American citizens traveling in Italy, calling those landmarks “potential targets” but also flagging possible threats to “churches, synagogues, restaurants, theaters and hotels” in Rome and Milan.