International pressure appears set to increase on the beleaguered regime of Syrian President Bashar al-Assad amid continuing violence in the Arab nation.

EU High Commissioner for Foreign Affairs and Security Catherine Ashton called Thursday for Assad to step down. The call came following talks in Moscow during which Syria shared the agenda with Iran and the International Atomic Energy Agency's report of credible evidence that Tehran is building a nuclear weapon.

The European Union has already imposed economic sanctions on the Assad government and more may follow.

Jordan's King Abdullah last week also called for Assad's departure, becoming the first Arab leader to do so.

The Arab League, meanwhile, is meeting Thursday in Cairo to discuss Assad's failure to keep promises made to release political prisoners and pull troops from cities and towns, where violent clashes between security forces and pro-democracy demonstrators over the past eight months have left an estimated 3,500 people dead.

Reports from the region indicate that the 22-member organization, which has suspended Syria's membership, may set about imposing economic sanctions.

The push for a tough Arab League stance apparently is being championed by Qatar but Saudi Arabia is said to be the driving force since Iran, Riyadh's regional nemesis, is an ally of the Assad government.

On the European front, Britain's former ambassador to Lebanon, Frances Guy, is to meet Syrian opposition figures in London. Talks with senior British government leaders are apparently also in the cards. And Britain, Germany and France are expected to call on the United Nations for a non-binding resolution condemning the killing of civilians by Assad's soldiers.

The U.N. Security Council, which authorized NATO military force to protect civilians from Libyan leader Moammar Gadhafi, has failed to act forcibly against Damascus, primarily because of opposition from Syria's trade partners Russia and China.

Although diplomatic moves to isolate the Assad regime and to build relationships with opposition leaders are reminiscent of actions prior to NATO's military campaign against Libya, observers note there are key differences. Unlike Libya's rebels, Syria's opposition groups haven't formed a government and don't control large areas of the country. Also unlike Libya, NATO action -- even with U.N. backing -- could lead to a confrontation with Syria's ally Iran.

"There is no appetite for that kind of action vis-a-vis Syria," U.S. Secretary of State Hillary Clinton said Friday in a television interview.

Street demonstrations against the authoritarian rule or Assad began in March to protest government corruption, the proscribing of political parties other than the Baath Party, and draconian security practices implemented under a decades-old state of emergency declaration.

The Syrian government, unused to defiance, reacted by sending troops into the streets. Photographs soon spread throughout the world of security forces shooting demonstrators.

The Syrian army, as well as the government, is dominated by Alawites, a Shiite Muslim sect. The majority of Syrians are Sunni Muslims, adding a sectarian flavor to the upheaval.

Clashes in outlying cities and towns spread and violence has reached the capital. On Sunday, members of the Free Syrian Army -- mainly army defectors -- were reported to have attacked an empty headquarters building of the Baathist Party in Damascus with rocket-propelled grenades. The attack, denied by the Assad government, came three days after rebel gunmen attacked the headquarters of air force intelligence in Harasta on the outskirts of Damascus.

The Assad regime blames the violence on outside forces, including Islamists. Peace in the country will come, Assad told The Sunday Times of Britain, only by standing firm against those plotting against his government.

"Syria will not bow down," he said. "The only way is to search for the armed people, chase the armed gangs, prevent the entry of arms and weapons from neighboring countries, prevent sabotage and enforce law and order."

In an effort to dampen protests, Assad has promised new national elections, but after eight months of violence and thousands of deaths the promise is likely to fall on deaf ears -- at home and abroad.