At least 24 Syrians were killed in violence on Friday and the military tried to halt a refugee exodus, opposition activists said, only four days before a troop pullback agreed by President Bashar al-Assad as part of a U.N.-backed peace plan.
The Syrian Observatory for Human Rights said shelling had killed at least 10 people, including four rebel fighters, in the flashpoint central city of Homs. Two soldiers died in separate clashes and one person was killed in the town of Douma, it said.
The British-based Observatory, using its network of contacts in Syria, also reported seven civilians and four soldiers killed in clashes and bombardments in Anadan, north of Aleppo.
The fresh violence erupted a day after U.N. Secretary-General Ban Ki-moon said the conflict was worsening and attacks on civilian areas persisted, despite assurances from Damascus that its troops had begun withdrawing under the peace plan.
U.N.-Arab League mediator Kofi Annan has said the government and opposition must stop fighting at 6 a.m. (0300 GMT) on April 12, if Damascus meets its deadline 48 hours earlier to pull back troops from cities and cease using heavy weapons.
Assad's opponents have accused the Syrian military of using the run-up to the ceasefire to intensify assaults. Syria has now charged insurgents with doing the same.
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In recent days terrorist acts committed by armed groups in Syria have escalated, especially since an understanding was reached on Kofi Annan's plan, Syria said in a letter to the United Nations released on Friday.
The international community and the Security Council must take the necessary measures to prevent and stop the funding of any terrorist activities against Syria, it said.
Syrian forces were laying mines near the border with Turkey to try to block a flow of refugees and supplies for insurgents, rebel activists and a Turkish official said.
The Syrians have been mining the border, especially the southern Idlib part which has been restricting the flow of refugees, said the official, who declined to give his name.
Turkey fears all-out war in Syria would unleash a flood of refugees. About half million fled to Turkey after the 1991 Gulf War. Ankara has stated for months that a mass exodus could oblige it to establish a safe zone on the Syrian side.
Turkey said there were now 23,835 Syrian refugees on its territory of whom 2,800 arrived on Thursday alone, more than double the highest previous one-day total.
The army is destroying buildings and bombing them till they turn to charcoal, said Mohammed Khatib, a refugee who said he came from Kastanaz, a Syrian town of 20,000 people.
TANKS IN ACTION
On Friday, activists reported tank fire in at least three urban centres of Syria - the town of Douma near Damascus, the restive city of Homs and Rastan, north of Homs.
At least 5 tanks and 10 buses loaded with security men and Shabiha (pro-Assad militia) entered Douma, one local activist said. There has been shelling on Douma since the morning.
In Rastan, an activist said Free Syrian Army rebels had confronted a morning tank thrust. They blocked the advance and the Assad army left. Then artillery started, he said.
Accounts are difficult to verify because Syria's government restricts access to independent journalists.
Assad blames the conflict on foreign-backed terrorists and has proposed a parliamentary election on May 7 among other reforms. His opponents dismiss these as a sham, saying it is impossible to have a valid vote while bloodshed continues.
Anti-Assad demonstrations broke out after Friday prayers in the eastern province of Hasakeh, in the town of Qamishli and Deir al-Zor city, activists said. Protesters carried the white and green rebel flag. Some saluted other rebel cities.
Loyalist forces have killed more than 9,000 people during the unrest, according to a U.N. tally. Syria says 6,044 have died, including 2,566 soldiers and police.
Western powers are not convinced Assad will honour the promised truce and believe he may seek loopholes giving him more time to cripple the Free Syrian Army (FSA) and deter protesters.
It is also uncertain whether the FSA has enough control over its fighters to enforce Annan's ceasefire deadline.
Syria's U.N. ambassador Bashar Ja'afari said the plan did not require any pullback of police - who have played a big role in the conflict as suggested by the state's own casualty toll.
Last year the opposition said troops had disguised themselves as police and repainted army vehicles in police colours before the arrival in December of Arab observers sent to monitor what proved an abortive Arab League peace plan.
A Norwegian general attached to U.N. peacekeeping arrived in Damascus on Thursday to examine prospects for an eventual U.N. ceasefire monitoring mission of up to 250 unarmed observers, something which would require a Security Council resolution.
(Writing by Douglas Hamilton; Editing by Alistair Lyon)