BEIRUT: Syrian troops stormed on Saturday at a central town and a northwestern region in search of opponents of the government as pressure on Damascus intensified to end an eight-month crisis that has left thousands of people dead, activists said.

The attacks on the town of Shezar in the central province of Hama and the restive Jabal al-Zawiya region near the Turkish border came a day after Syria agreed in principle to allow Arab observers into the country to oversee a peace plan proposed by the 22-member Arab League.

The British-based Syrian Observatory for Human Rights and the Local Coordination Committees said that land and cellular telecommunications as well as electricity have been cut in the Jabal al-Zawiya region where army defectors have been active for months.

Syria's acceptance came on Friday after surprisingly heavy pressure from the Arab League, which brokered the plan and this week suspended Syria from the 22-member organization for failing to abide by it.

On Wednesday, the league gave Damascus three days to accept an observer mission or face economic sanctions.

The latest attacks came amid building international pressure on Syrian President Bashar Assad.

An official at Britain's Foreign Office said Foreign Secretary William Hague intends to meet opposition representatives in London on Monday.

Meanwhile, French Foreign Minister Alain Juppe called on the UN Security Council to strengthen sanctions against Assad's regime.

However, Russia, which holds veto power in the council, urged caution in moving against Damascus.

In Washington, State Department spokesman Mark Toner said the US has seen no signs that Syria's government will honor the Arab League proposal.

Violence has escalated in Syria over the past week, as army dissidents who sided with the protests have grown bold, fighting back against regime forces and even assaulting military bases.

Activist groups said security forces on Friday killed at least 16 anti-government protesters.

Also, on Saturday, Turkish Prime Minister Recep Tayyip Erdogan, commenting on the deteriorating relations between his country and its southern neighbor, accused Syria of not fulfilling promises for reform or to stop the bloodshed.

''In the past nine years, it was Syria and the Syrian people rather than Turkey that had benefited from the Turkish-Syrian friendship,'' Erdogan said.

''Unfortunately, the Syrian administration has acted in a reluctant and insincere manner in keeping its promises.''

''If there is a change of policy, it is not by Turkey but by Syria.

Syria has not kept its promises to Turkey, to the Arab League or to the world.

It made promises but did not fulfill them. It has not acted in a sincere trustworthy manner,'' he said.

The attacks on Jabal al-Zawiya came two days after an army force in the nearby area of Wadi al-Deif came under attack by army defectors, a clash that lasted four hours and left an unknown number of casualties among troops loyal to Assad, an activist said.

The activist, who spoke on condition of anonymity because of the sensitivity of the matter, said troops fired from heavy machine guns mounted on armored personnel carriers on the attackers.

The Arab League observer mission aims to prevent violence and monitor a cease-fire that Damascus agreed to last week, but has been unwilling or unable to implement.