BEIRUT (Reuters) - Syria says the year-old revolt to topple President Bashar al-Assad is over, but the army again shelled opposition areas on Saturday and rebels said they would not cease fire until tanks, artillery and heavy weapons are withdrawn.
Washington and Gulf Arab states urged peace envoy Kofi Annan to set a timeline for "next steps" if there is no ceasefire, and Saudi Arabia repeated a call for rebels to be armed.
Annan has said neither measure would be helpful. The former U.N. chief's mission has brought no respite in the killings.
Syria also said it would keep its forces in cities to "maintain security" until it is safe to withdraw in line with the peace deal, which Assad has said he accepts.
Annan's plan says the army must stop violence immediately and be the first to withdraw forces.
"We cannot accept the presence of tanks and troops in armored vehicles among the people," a spokesman for Free Syrian Army commanders inside Syria said.
"We don't have a problem with the ceasefire. As soon as they remove their armored vehicles, the Free Syrian Army will not fire a single shot," Lieutenant Colonel Qassim Saad al-Din told Reuters by telephone from Homs.
A rebel officer in Damascus said separately: "When Assad's gangs stop the shelling and killing of civilians, then our leaders can issue an order to stop operations and we will commit to it to show our good intentions."
Opposition activists reported 25 people killed and five bodies found bearing signs of torture, including two children.
A protest singer in Kafr Ruma was killed when his house was raided. A young man and his sister were shot dead when state forces stormed their village, and a man died of gunshot wounds inflicted during a protest in Damascus.
Artillery and mortars pounded a pro-opposition part of Homs city, killing one. Ten deaths were reported in Homs province.
"Mortars are falling every minute and the sounds of explosions are shaking the (Khalidiya) neighborhood," the Syrian Observatory for Human Rights said.
Rocket fire killed a child in the al-Bayyada area of Homs and a man was killed in crossfire in clashes near a checkpoint.
In southern Deraa province, five were killed by machinegun fire in Kharbat Ghazaleh and three died from wounds sustained in clashes on Friday. Rebels killed six soldiers, including a lieutenant colonel in Deir al-Zor, the Observatory said.
Despite the violence, Damascus says it has the upper hand.
"The battle to topple the state is over," Syrian Foreign Ministry spokesman Jihad al-Makdissi told Syria TV late on Friday. "Our goal now is to ensure stability and create a perspective for reform and development in Syria while preventing others from sabotaging the path of reform."
His assertion follows army victories over rebel strongholds in the cities of Hama, Homs and Idlib, and Assad's acceptance this week of Annan's plan that does not demand he step down.
The political opposition remains divided and prospects of Western-led military intervention are close to zero.
Assad's opponents have not yet formally accepted the plan.
They were due to meet the foreign ministers of allied Western powers, including U.S. Secretary of State Hillary Clinton, on Sunday at a "Friends of Syria" conference in Turkey, which provides a safe haven for Syrian rebels.
After Clinton met Gulf foreign ministers in Riyadh on Saturday, they said Annan should set a timeline for unspecified measures should his efforts fail to halt the bloodletting.
"Given the urgency of the joint envoy's mission, (U.S. and Gulf ministers) urged the joint envoy to determine a timeline for next steps if the killing continues," a statement said.
Saudi Foreign Minister Saud al-Faisal told a news conference with Clinton: "The arming of the opposition is a duty, I think, because it cannot defend itself except with weapons."
Assad has endorsed Annan's six-point peace plan, which has the U.N. Security Council's unanimous backing, but Western leaders say the 46-year-old Syrian leader has broken similar promises before and must be judged by actions not words.
Syria's Makdissi said Annan, who met Assad in Damascus on March 10, had acknowledged the government's right to respond to armed violence during the ceasefire phase of the peace plan.
"When security can be maintained for civilians, the army will leave, he said. "This is a Syrian matter."
Annan's plan says Syria must stop putting troops into cities forthwith and begin taking them out.
"The Syrian government should immediately cease troop movement towards, and end the use of heavy weapons in, population centers, and begin pullback of military concentrations in and around population centers," it states.
A sustained end to violence by all sides would be supervised by a U.N. team of around 250 monitors, diplomats said.
Western diplomats say the key to any ceasefire deal lies in the sequencing of the army pullback and ending rebel attacks.
They say the opposition won't feel safe negotiating before the army stops shooting, but also note it would be impractical to expect a complete government pullout before rebels respond.
More than 9,000 people have been killed by Assad's forces during the revolt, according to the United Nations, while Damascus says it has lost about 3,000 security force members.
Western and Arab foreign ministers backing Syrians trying to topple Assad will seek clear endorsement of the Annan plan from the Syrian National Council (SNC), although they themselves doubt whether Assad will genuinely try to implement it.
In Libya a year ago, the West and the Arabs quickly granted recognition to a revolutionary national council as the sole legitimate government of Libya. They are not close to doing the same for the splintered SNC in Syria, diplomats say.
There is also little chance they will agree to arm rebels.
If Assad fails to keep his word, Annan would have to decide whether to call time and tell the United Nations he has failed to make peace through a "Syrian-led process".
The issue would then return to the U.N. Security Council, with increased pressure on Assad's allies Russia and China, which have endorsed Annan's mission, to get tough with Damascus.
Additional reporting by Adrian Croft in London, John Irish in Paris, Steve Gutterman in Moscow, Dominic Evans in Beirut; Writing by Douglas Hamilton; Editing by Alistair Lyon