Regime forces battled rebels and carried out raids across Syria Sunday in a surge of violence that killed 23 people, monitors and activists said, as a tenuous UN-backed truce entered its second month.
The fresh wave of bloodletting came as the UN mission in Syria said it now has 189 military observers on the ground, nearly two-thirds of its planned strength of 300.
The observers are tasked with shoring up the ceasefire brokered by UN-Arab League peace envoy Kofi Annan that was supposed to take effect on April 12 but which has been broken daily.
"There are now 189 monitors on the ground," Hassan Siklawi, a representative of the UN mission in Syria, told AFP on Sunday.
The deployment of extra monitors came as the Syrian Observatory for Human Rights reported at least 23 people killed on Sunday, including five soldiers who died in gunfights with armed rebels in the southern province of Daraa.
Two civilians were killed in the crossfire, it added.
In central Hama province, five people were killed by gunfire, including a woman, when regime forces raided the village of Al-Tamanaa Al-Ghab, the Britain-based watchdog said, adding that 18 people were wounded and several houses set on fire.
A man and his son were killed and 10 other people wounded when they were shot by regime forces in the town of Qusayr in central Homs province, where armed rebel groups have strongholds, the watchdog added.
Also in Homs, a civilian was killed by sniper fire in the town of Rastan.
Three civilians were killed by regime forces near Damascus, two in Idlib province and one in Aleppo province, while two army deserters were killed, one in Douma, the other in the eastern province of Deir Ezzor, the watchdog said.
And in neighbouring Lebanon, sectarian clashes in the northern city of Tripoli between factions supporting and opposed to the Syrian revolt left one person dead on Sunday, a security source said.
The violence in Syria has escalated over the past week, despite the arrival of more ceasefire observers, with twin suicide bombings in Damascus on Thursday killing 55 people and wounding 372.
The attacks have raised fears that extremist elements are taking advantage of the deadlock in Syria to stoke the unrest.
Al-Nusra Front, an Islamist group unknown before the Syrian revolt, released a video on Saturday claiming responsibility for the Damascus attacks as revenge for regime bombing of residential areas in several parts of the country.
Claims by the group, including for past bombings, have been difficult to verify.
The head of the dissident Free Syrian Army in remarks published on Sunday charged that Al-Qaeda has links with the powerful airforce intelligence of the regime of President Bashar al-Assad.
"If Al-Qaeda militants have indeed entered the country, it happened with the cooperation of that agency," FSA chief, Colonel Riyadh al-Asaad, told Kuwait's Al-Rai newspaper.
Asaad denied claims by Damascus that jihadist and Salafi groups were active in Syria, and blamed the Syrian regime for Thursday's devastating bomb blasts in the capital, calling for an international investigation.
State media has accused the West and its regional allies of opening the door to Al-Qaeda through its backing of the opposition.
A Turkish journalist held prisoner in Syria for two months said on Sunday that he and a Turkish cameraman feared they would die, and spent 55 days isolated in cramped cells where they slept on the floor.
The two Turkish journalists, who were arrested by a pro-regime militia in March and handed over to Syrian intelligence, returned to Istanbul this weekend after being freed thanks to Iranian mediation.
More than 12,000 people, the majority of them civilians, have died since the Syrian uprising began, according to the Observatory, including more than 900 killed since the April 12 truce went into effect.