By Khaled Oweis
AMMAN, Aug 4 Reuters) - At least 45 civilians were killed in a tank assault by Syrian President Bashar al-Assad's forces to occupy the center of Hama, an activist said on Thursday, in a sharp escalation of a military campaign aimed at ending an uprising against his rule.

Reacting to intensifying assaults on Syrian cities and towns, the U.N. Security Council overcame deep divisions and condemned Assad's bloody crackdown on civilian protesters. It was the first substantive action by the United Nations on Syria's five-month-old uprising for political freedoms.

An activist who managed to leave the besieged city told Reuters that 40 people were killed by heavy machinegun fire and shelling by tanks in al-Hader district north of the Orontes river on Wednesday and early on Thursday.

The activist, who gave his name as Thaer, said five more people from the Fakhri and Assa'ad families, including two children, were killed as they were trying to leave Hama by car on the al-Dhahirya highway.
Syrian authorities have expelled most independent media, making it difficult to verify witness accounts and official statements.

Residents earlier said tanks had advanced into central Hama on Wednesday after heavily shelling the city and occupied the main Orontes Square, the site of some of the largest protests against Assad, who succeeded his father, the late President Hafez al-Assad, in 2000.

Snipers spread onto rooftops and into the nearby citadel. They said shelling concentrated on al-Hader district, large parts of which were razed in 1982 when forces loyal to Hafez al-Assad overran Hama to crush Islamist insurgents, killing many thousands of people.

Human rights campaigners say more than 90 people, not counting the latest toll, have been killed in Hama since Assad, from Syria's minority Alawite sect, launched a military assault on Sunday to crush dissent against his autocratic rule.

The assaults triggered international condemnation and calls from U.S. senators for sanctions on Syria's energy sector, concentrated in eastern Syria.
Last week tanks moved into the eastern provincial capital of Deir al-Zor and the town of Albu Kamal on the border with Iraq's Sunni heartland. Both town have also witnessed large pro-democracy protests.

TANKS USED WITH "TARGETED FEROCITY"

"The security apparatus thinks it can wrap this uprising up by relying on the security option and killing as many Syrians as it thinks it will take," a diplomat in the Syrian capital said.
"Tanks are firing their guns at residential buildings in Hama and Deir al-Zor after the two cities were left for weeks to protest peacefully. This is the first time the regime is using tanks with such targeted ferocity," the diplomat said.
The official Syrian news agency said "armed terrorist groups" had abducted three oil-well guards in Deir al-Zor on Wednesday, and killed one policeman.

Authorities say the army had entered Hama to confront "terrorists" who were intimidating inhabitants. State television broadcast footage of armed men who it said had attacked security forces and government buildings in Hama.

U.S., TURKEY, HARDEN STANCE

A Syrian pharmacist who managed to talk with her family in Hama told Reuters that they had tried to flee but that the 'shabbiha' were randomly shooting residents. Several buildings in Hama had caught fire from tank shelling and snipers were in position on rooftops in Orontes Square, she said.

The Local Coordination Committees grassroots activists' group said in a statement that the authorities were trying prevent any news emerging on the ferocity of the assault. The group said it could no longer contact its members in Hama.
"Communications have been totally cut off in Hama, together with water and electricity. There is a big movement of refugees trying to flee the city," the statement said.

In New York, Indian Ambassador Hardeep Singh Puri, president this month of the Security Council, read out a statement condemning "widespread violations of human rights and the use of force against civilians by the Syrian authorities."

But it urged all sides to act with restraint, reflecting divisions among the West on one hand and China and Russia, which has a naval base in Syria, on how to deal with Assad.
The only dissenter in the council was Lebanon, where Syrian influence remains strong after a 29-year military presence that ended in 2005. In a rare move, Beirut dissociated itself from a formal statement agreed by the other 14 members.

Syria backs the militant Lebanese Shi'ite group Hezbollah, against the wishes of Syria's Sunni majority population.
The U.N. document agreed after three days of hard bargaining, instead of a full council resolution the West would have preferred, urged Damascus to fully respect human rights and comply with its obligations under international law.

The White House slightly hardened its stance against Assad on Wednesday, saying the United States viewed him as the cause of instability in the country.
"Syria would be a better place without President Assad," White House spokesman Jay Carney said at a news conference.
Turkish Deputy Prime Minister Arinc Bulent, whose country had grown close to Assad in recent years, issued the strongest condemnation yet of the Syrian president by a Turkish leader.

"I'm saying this on my behalf, what's going on in Hama today is an atrocity ... Whoever carries this out can't be our friend. They are making a big mistake," he said.
The plight of Hama has prompted many Syrians to stage solidarity marches since the start of the holy month of Ramadan earlier this week.

The Syrian Revolution Coordination Union said seven demonstrators were shot dead in attacks by security forces on protests after nightly Ramadan prayers across Syria on Wednesday.
(Reporting by Khaled Yacoub Oweis, Amman newsroom; Editing by Michael Roddy)