At least 95 people were killed on Sunday when the military launched an attack on the flashpoint protest city of Hama in central Syria, a human rights activist said.

Ammar Qorabi, who heads the National Organisation for Human Rights, also said army attacks across the country on Sunday killed at least 121 people and wounded dozens more.

"The army and security forces launched an attack on Hama and opened fire on civilians, killing 95 people," Qorabi said, adding he had a list of names of 62 of the dead.

He said that elsewhere, "19 people were killed in Deir Ezzor in the east, six more died in Harak in the south and one in Al-Bukamal," also in the east.

Earlier, Rami Abdel Rahman of the Britain-based Syrian Observatory for Human Rights reported a death toll in Hama of 45, but said that number could rise because of many seriously wounded and a lack of medical supplies.

He also reported six dead and 50 wounded in Deir Ezzor and three killed and dozens wounded at Harak in the Deraa region.

One resident reached by phone told AFP the army entered Hama at around 6:00 am (0300 GMT) in an apparent operation to wrest back control after almost two months during which security forces were absent.

Another said: "Five tanks are now deployed outside the governor's palace," and spoke of intermittent gunfire.

The official SANA news agency reported two members of the security forces killed on Sunday by "armed groups" in Hama.

"Two law enforcement members were martyred by armed groups in Hama who set police stations on fire, vandalised public and private properties, set up roadblocks and barricades and burned tyres at the entrance of the city and in its streets," an English-language report on the SANA website said.

It said soldiers were dismantling the barricades.

"Armed groups of scores of gunmen are stationed on the rooftops of the main buildings in the streets of the city, carrying up-to-date machine guns and RPGs and shooting intensively to terrorise citizens," it quoted unidentified residents as saying.

The Syrian Observatory said the army also launched an operation against Muadhamiya in the Damascus region.

"Security forces launched an offensive at 5:00 am (0200 GMT) on Muadhamiya from the north, with tanks blocking the southern, eastern and western entrances to the town," Abdel Rahman said.

The Syrian League for the Defence of Human Rights reported more than 300 people detained in Muadhamiya, where electricity supplies and communications had been cut.

The eastern oil hub of Deir Ezzor and Hama have been rallying points for pro-democracy protests since mid-March.

In 1982, an estimated 20,000 people were killed in Hama when the army put down an Islamist revolt against the rule of President Bashar al-Assad's late father, Hafez.

The president replaced the governor of Hama after a record 500,000 protesters rallied in the opposition bastion on July 1 calling for the fall of the regime.

Activists said at the time it was the single largest demonstration of its kind since the pro-democracy movement erupted on March 15.

Since security forces gunned down 48 protesters in the city on June 3, Hama had escaped the clutches of the regime, activists say. The next day, more than 100,000 mourners were reported to have massed at their funerals.

On Saturday, Abdel Rahman said troops shot dead three people who stoned a military convoy heading to quell growing anti-regime dissent in Deir Ezzor.

He said about 60 military vehicles including tanks, personnel carriers and trucks crammed with soldiers deployed there.

A man identifying himself as a Syrian army colonel told AFP in Nicosia that he had defected and has "hundreds" of troops under his command ready to confront the regular army in Deir Ezzor.

"I warn the Syrian authorities that I will send my troops to fight with the (regular) army if they do not stop the operations in Deir Ezzor," Riad al-Asaad said.

"I am the commander of the Syrian Free Army," he said, adding that he commanded "hundreds" of troops and was calling from inside Syria "near the Turkish border."

His claim could not be independently verified.

Deir Ezzor, the main oil- and gas-producing region in Syria, produces 380,000 barrels of oil per day and has seen almost daily demonstrations against the regime.

On Friday, at least three people were killed there when security forces opened fire on 300,000 mourners at the funerals of three people killed the previous day, activists said.

Since anti-regime protests broke out, the crackdown on dissent has resulted in the deaths of more than 1,500 civilians and more than 360 members of the security forces, according to a Syrian Observatory toll.

More than 12,000 people are also reported to have been arrested in the crackdown.