United Nations envoy Kofi Annan speaks during a press conference in Damascus on Sunday. Annan help two meetings with Syrian President Bashar Assad to discuss proposals for stopping violence and starting a political dialogue. (Muzaffar Salman/AP)

An international push to end Syria’s conflict stalled Sunday as U.N. envoy Kofi Annan left Damascus without a cease-fire deal and President Bashar al-Assad’s forces pounded opposition areas and clashed with rebels throughout the country.

Western and Arab powers are struggling for ways to stem the bloodshed in the year-old conflict while the regime and the opposition reject dialogue. Annan, a former U.N. secretary general, appeared to make little progress during two visits with Assad in his first trip to Syria as the joint U.N.-Arab League envoy.

Annan was seeking an immediate cease-fire to allow for humanitarian aid and the start of a dialogue between all parties on a political solution. After meeting with Assad on Sunday, Annan said he had presented steps to ease the crisis, but he gave no details.

“Once it’s agreed, it will help launch the process and help end the crisis on the ground,” he told reporters. Annan called for “reforms that will create a strong foundation for a democratic Syria — a peaceful, stable, pluralistic and prosperous society, based on the rule of law and respect for human rights.”

Assad told Annan on Sunday that a political solution is impossible as long as “terrorist groups” threaten the country, according to Syria’s state news service — which reported identical comments after the men met Saturday. The regime blames the uprising on alleged armed groups acting out a foreign conspiracy.

Meanwhile, government troops shelled areas in and around the northern city of Idlib, activists said, part of a campaign launched Saturday to crush the opposition in its stronghold along the border with Turkey. In some areas, they clashed with rebels fighting under the banner of the loose-knit Free Syrian Army.

The Britain-based Syrian Observatory for Human Rights, which relies on a network of activists throughout Syria, said 16 civilians had been killed in attacks by Syrian forces or in clashes with local rebels in Idlib province. More than five government soldiers also were killed.

An AP photographer in Turkish border villages heard a constant pounding of artillery, and Turkish residents said they saw Syrian refugees crossing during lulls.

Activists said Syrian forces targeted neighborhoods in the central city of Homs on Sunday with shells and rocket-propelled grenades.

Other activists said government forces shelled a bridge on a road to the Lebanese border often used by families fleeing violence. It was unclear whether the bridge was destroyed.

The Syrian Observatory for Human Rights said 25 civilians had been killed in military attacks and in clashes between army and rebel forces across Syria on Sunday. Another group, the Local Coordination Committees, said 32 were killed.

The death tolls could not be independently verified. The Syrian government rarely comments on specific incidents and bars most media outlets from operating in the country.

— Associated Press

AP writers Albert Aji in Damascus and Suzan Fraser in Ankara, Turkey, contributed to this report.