US-led coalition warplanes have pounded the Islamic State group in Syria after the Paris attacks, with French raids hitting IS stronghold Raqa and another strike destroying dozens of oil tankers.

In its first major military response to Friday's attacks in Paris, France said 12 of its warplanes had hit IS positions in Raqa, the jihadists' de facto Syrian capital.

In Paris, President Francois Hollande said France would "intensify" operations in Syria.

"We will continue the strikes in the weeks to come," he told an exceptional meeting of both houses of parliament.

Activists and a monitoring group said the wave of strikes had shaken Raqa and sparked panic, but the number of casualties was not yet known.

"There were at least 36 explosions overnight in Raqa city, some caused by air strikes and some by weapons and explosives detonating after being hit," said Rami Abdel Rahman, director of the Syrian Observatory for Human Rights.

"The blasts shook the entire city," he told AFP.

France's defence ministry said warplanes, including Rafale and Mirage fighters, had dropped 20 bombs on targets including a command post, a recruitment centre and arms depots south of Raqa.

A training camp west of the city was also hit, it said.

The strikes came after IS claimed responsibility for the bomb and gun attacks that killed at least 129 people in Paris.

"IS has imposed a security alert on the city, and it is difficult to confirm information about casualties from hospitals there," Abdel Rahman said.

He said IS had already imposed security measures in Raqa after previous raids, including evacuating some headquarters and moving the families of foreign fighters elsewhere.

- 'French strikes could help' -

An activist group, Raqa is Being Slaughtered Silently (RBSS), said the raids caused "panic" among civilians but that no civilians appeared to have been killed.

"IS is not allowing people to walk around and has cut off all the electricity," said RBSS activist Abu Mohammad, who is from Raqa.

Speaking via the Internet, he said IS members typically take refuge in bomb shelters during strikes.

Raqa is regularly targeted by US-led coalition aircraft, Syrian warplanes and more recently Russian air strikes which began on September 30.

Experts said France's strikes could be useful if they were based on solid information, but warned that intelligence gaps and the risks of civilian deaths have long been obstacles to targeting IS.

"If the French do have good intelligence on where they're targeting and they are doing it for good reason rather than to just lash out, then it could in the long term build into something useful," analyst and researcher Charlie Winter told AFP.

He said IS's top leadership was unlikely to be in Raqa, and that it would seek to capitalise on any civilian casualties for propaganda purposes.

- Going after IS revenues -

The US-led coalition has targeted IS in Syria since September 2014, expanding a campaign that began in Iraq.

The coalition has killed hundreds of IS members, the Observatory says, but has had a limited effect on its ability to hold territory.

On Monday, the Pentagon said coalition strikes on Sunday destroyed 116 fuel trucks used by the jihadists near Albu Kamal, an IS-held town in Deir Ezzor province on the border with Iraq.

A coalition spokesman said the strike hit parked trucks, "the first time that we've hit so many at once".

The spokesman also said there was a leaflet drop ahead of the strikes "to encourage truck drivers to stay away from the targeted trucks".

IS reportedly makes millions of dollars from oilfields it controls.

The coalition has vowed to target IS's financial resources, the spokesman said, adding: "This strike was part of that strategy to start degrading their financial ability."

A US-backed alliance of Kurdish and Arab forces fighting IS in northeast Syria announced Monday it had driven the jihadists from 196 villages.

Syrian Democratic Forces spokesman Talal Ali Sello said that "between October 30 and November 13, an area of 1,362 square kilometres (545 square miles) was cleansed of IS".

Canada said its forces had also targeted IS in Iraq on Sunday as new Prime Minister Justin Trudeau comes under pressure after the Paris attacks to reconsider a campaign pledge to have Canadian forces in the coalition halt such strikes.

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