A UN observer stands next to a Syrian army tank near Damascus Two explosions rocked central Damascus on Saturday, a watchdog said, a day after Syrian security forces killed at least 37 civilians despite the presence of UN observers. "One bomb exploded in As-Saura Street," an key commercial artery in the capital, while the location for the other was uncertain, Rami Abdel Rahman of the Syrian Observatory for Human Rights told AFP.
Abdel Rahman, speaking on the phone from Britain where his rights watchdog is based, accused the government of carrying out the bombings to prevent people attending funerals for nine civilians killed in Damascus on Friday.
The nine died during demonstrations and funerals in the neighbourhoods Kfar Sousa and Tadamon.
"This is the highest death toll we have seen inside Damascus" since a ceasefire took hold in April 12, added Abdel Rahman, whose group says more than 600 people have been killed nationwide during the tenuous truce.
Opposition bloc the Syrian National Council called in a statement early Saturday on the UN observers to visit Kfar Sousa and Tadamon, "where the funerals of the martyrs killed Friday will be held."
The peace agreement was brokered by UN-Arab League envoy Kofi Annan, whose office said Friday that his peace plan was "on track."
Syrian activists claim at least 37 people were killed by security forces on Friday, as protests flared across the country against President Bashar al-Assad's regime. The Local Coordination Committees (LCC) activist network claimed three Syrians  were killed in Aleppo, including a 16-year-old, together with two each  in Deir al-Zor, Homs and Hama and one in Deraa.It also reported that seven people were killed in the al-Tadamun neighbourhood of Damascus.Thousands of protesters took to the streets after Friday prayers with renewed calls for Assad's departure.
The opposition Syrian National Council (SNC) earlier called for a nationwide student strike in response to the assault by security forces on Aleppo University on  Thursday which activists said left at least four dead.
Protests were reported in Aleppo, Damascus, Damascus suburbs, Deir al-Zor, Deraa, al-Hasakeh, Homs, Idlib, Lattakia, Hamdanieh, Haretan, Tareeq Halab, Ferdaws, Tal Refaat, Ashrafieh, Tafad, Sheaar and Qamishli. Twent-three people were  reported to have died in Aleppo  on Thursday. In a statement, the SNC, an umbrella opposition organisation based outside the country, urged the strike "in solidarity with students at Aleppo University."
The Syrian monitoring group also said a man was shot dead by security forces at the Balooni Prison, prompting a protest in the area against the regime.
Elsewhere in the city, gunfire was heard close to the Hada Shaarawi checkpoint followed by loud explosions amid a widespread security presence with regime tanks seen near Tadmor Central Prison.
In Hama, three people were reported to have been killed when troops opened fire on their vehicle near an intersection.
In Idlib, explosions were heard in several areas accompanied by heavy gunfire, the LCC reported.
Human rights group Amnesty International, in their latest report on Friday said  that Syrian forces were executing scores of suspected opposition sympathisers in the northern city of Idlib, burning their bodies in piles or torching them in their homes then instructing family members to find them.
Three people are said to be in a critical condition after the assault on Aleppo University on Wednesday night.
The British-based Syrian Observatory for Human Rights said some 200 students were  arrested during the pre-dawn raid.
Following the violence, the university, the country’s second-largest, announced it was suspending classes until final exams on May 13.
Rami Abdel Rahman, head of the Observatory, said the events could mark a turning point for Syria’s second city and commercial powerhouse, which has remained relatively calm since the uprising against Assad’s regime broke out in March last year.
The head of the UN's military observer mission in Syria, Major General Robert Mood, said on Thursday that it was the responsibility of the Syrian army to make the first move to halt the violence, while the White House said theinternational community must “admit defeat” if a UN-backed peace plan fails.     
“If you have two individuals using on each other all their weapons, who is going to be the first one to move the finger? Who is going to be the first one to make the move?” Mood asked, during a visit to the battered central city of Homs.
“My approach to that is that the strongest part needs to make the first move,” he told reporters, according to Reuters.
“I was referring to the Syrian government and the Syrian army. They have the strength, they have the position and they also have the potential generosity to make the first step in a good direction,” he said, when pressed on whether he was speaking about the regime forces.
State news agency SANA said Mood visited the town of Lattakia on Friday and left saying it was "calm and peaceful".                       
Ahmad Fawzi, international mediator Kofi Annan's deputy, has however suggested more patience was needed with the plan. He told the Reuters news agency: "I would say that the Annan plan is on track and a crisis that has been going on for over a year is not going to be resolved in a day or a week. There are signs on the ground of movement (towards compliance with the plan), albeit slow and small."
Fawzi said there will be "around 50 observers" on the ground by the end of Friday. He added that that the UN so far has obtained commitments from nations for 150 of the 300 observers that the UN security council authorised, suggesting it iwas still struggling to make up the numbers.
The United Nations has accused both sides to the conflict of failing to abide by the terms of the ceasefire which it has admitted was not holding.
Annan's plan calls for a halt to fighting, the withdrawal of heavy weapons from urban areas, a daily humanitarian ceasefire, media access, an inclusive political process, and the right to demonstrate as well as the release of detainees.
Some 300 unarmed UN observers are to oversee the truce. An advance team began arriving in the country last month and their number has slowly increased and is supposed to reach the full complement in coming weeks.
Although the level of violence has gone down since the truce went into effect, there are still daily clashes and casualties reported.
The Observatorysaid more than 600 people have died since the truce went into effect, the majority of them civilians. Overall, more than 11,000 people have died since the uprising broke out in March last year, according to the Observatory’s figures.