Syrian activists reported military attacks on two towns and no large-scale troop pullout Tuesday, the day President Bashar al-Assad was to halt the use of heavy weapons and withdraw his forces from urban areas under an internationally brokered truce.

The London-based Syrian Observatory for Human Rights said government forces shelled the central city of Hama and the northwestern town of Mareh while parts of Homs came under mortar fire.

Syrian Foreign Minister Walid al-Moallem said Damascus had already begun withdrawing army units from some Syrian cities but that the U.N.-brokered cease-fire must start simultaneously with the deployment of the international observer mission.

He was speaking in Moscow after talks with his Russian counterpart, Sergei Lavrov. Russia has been one of few world powers to offer some support to Mr. Assad in his bloody standoff with protestors but has also backed U.N.-Arab League envoy Kofi Annan's plan to end the violence.

On Monday, Syrian forces opened fire across two tense borders. The violence killed a television cameraman in Lebanon and at least two people at a refugee camp in Turkey.

Activists reported more than 125 people killed since Sunday within Syria as forces loyal to Mr. Assad continue to shell buildings and shoot at residents of rebellious cities.

The deal brokered by Mr. Annan says Syria must begin pulling its troops out of population centers by Tuesday morning, with a full cease-fire by both sides within 48 hours. But hopes for the plan dimmed after the fresh wave of violence and new demands by the government for written guarantees that the opposition will lay down arms first.

Turkish state-run television reported that Deputy Foreign Minister Naci Koru said Tuesday's deadline for the withdrawal has become “void at this stage.”

The United States and the United Nations condemned Syria's attack on the refugee camp in the border town of Kilis as well as the death of the TV journalist in Lebanon. A State Department spokeswoman said Washington is “not hopeful” Tuesday's cessation of hostilities will take place. But she did not give up hope on Mr. Annan's efforts to end the bloodshed.

The former U.N. secretary-general is due to visit one of the refugee camps in Turkey Tuesday ahead of a visit to Iran later this week aimed at continuing his mediation efforts.

U.N. spokesman Martin Nesirky said Monday “the deadline has not shifted” and that “Syrian authorities need to implement the promises and the commitments that they have entered into fully and unconditionally.”

The Carnegie Endowment's Sinan Ulgen said Monday's attack on the Turkish refugee camp may help Ankara convince its international partners to shift policy on the Assad government. Turkey has set up camps for Syrians fleeing Mr. Assad's bloody crackdown on a 13-month anti-government uprising.

Also Monday, Human Rights Watch said Syrian forces have summarily executed more than 100 people, mostly civilians, during the past four months, mostly in March. Monday's report said this includes several mass executions in the restive provinces of Homs and Idlib. The New York-based rights group said it only included cases corroborated by witnesses, but has received more reports of similar incidents.

U.N. officials say more than 9,000 people have been killed in Syria since the uprising began 13 months ago.