"Troops and armored vehicles stormed Bab Amro neighborhood of Homs early evening. The neighborhood is witnessing a massacre. The number of dead are likely to go up because there are seven out of 25 wounded in critical condition," Rami Abdelrahman, director of the Syrian Observatory for Human Rights, told Reuters.

Syria said the army pulled out of the central city of Hama after a 10-day assault on a symbolic center of protest against President Bashar Assad's 11-year rule, but tank attacks in towns north of Hama killed a woman and injured 13 people, an activist group said.

In Deir Al-Zour, another bastion of dissent against Assad's rule, residents reported heavy gunfire as troops deployed across the eastern city, making arrests and spraying pro-Assad slogans on buildings.

The Syrian Observatory for Human Rights said at least one woman was killed and 13 people were wounded when 12 tanks and armored vehicles, along with 10 large buses full of troops, entered the towns of Taftanaz and Sermin, around 30 km from the border with Turkey.

In nearby Binnish, rights campaigners said Syrian forces killed four villagers on Tuesday. "Daily protests in the region have been unabated since the start of Ramadan (on Aug. 1)," a local resident, who gave his name only as Ali, told Reuters by telephone.

In Deir Al-Zour, witnesses said Wednesday tanks and armored vehicles had spread across the city, and that residents had reversed earlier pledges to resist any army assault by force.

"The inhabitants of Deir Al-Zour have taken a collective decision not to resist, so as not to give excuses to the authorities to spread their propaganda about terrorists and armed groups," one resident said.

"We are hearing the sound of machine guns and shells," he said, adding he heard that soldiers and military intelligence officers had a list of 364 activists they were hunting.

He also said he saw troops spraying slogans on houses such as "Assad or no one", "The people want the army to come in."

On Tuesday night, he said, people had offered to share fruit and water with soldiers at one of the main roundabouts in the city. "A captain jumped from an APC and told soldiers not to accept anything. He then fired about 30 bullets in the air from his AK-47 in the air to disperse the crowd," the resident said.

Turkish Prime Minister Recep Tayyip Erdogan, who sent his foreign minister to Damascus on Tuesday to urge an end to the bloodshed, said the Syrian state "is pointing guns at its own people".

"Turkey's message to Assad is very clear: stop all kinds of violence and bloodshed," Erdogan said.

The Turkish leader said he hoped that Assad, confronting nearly five months of pro-democracy demonstrations, would take steps within 10 to 15 days toward promised political reforms.

"Our ambassador went to Hama and said that the tanks, security forces had started to leave Hama. This is highly important to show that our initiatives had positive results," Erdogan said in televised remarks, addressing his party members in Ankara.

In Washington, the White House said President Barack Obama believes Syria would be better off without Assad and the United States plans to keep pressure on the Syrian government. "We are all watching with horror at what he is doing to his own people," White House spokesman Jay Carney said.

Earlier the US Treasury Department announced new sanctions which it said were aimed at the financial infrastructure helping to hold up Assad's government. It said it was designating the Commercial Bank of Syria, a Syrian state-owned financial institution, and its Lebanon-based subsidiary, Syrian Lebanese Commercial Bank, under a presidential executive order that targets proliferators of weapons of mass destruction and their supporters.

It also designated Syriatel, Syria's largest mobile phone operator, under an executive order targeting Syrian officials and others responsible for human rights abuses in the country.

The US ambassador to the United Nations said his country had evidence of "crimes" in Syria and was ready to use it to step up pressure on Assad. Speaking ahead of a UN Security Council meeting on the Syrian crackdown, Ambassador Susan Rice said there would be more international action against Assad who has "lost his legitimacy to rule."