Car bombs have exploded in the Syrian capital and the northwest city of Idlib, as opposition activists report dozens of deaths elsewhere in the country.
A suicide bomber detonated an explosives-packed vehicle in the Damascus suburb Sayyida Zeinab on Thursday, wounding 14 people and damaging one of Shia Islam's holiest shrines, according to state media and witnesses.
State news agency SANA said the vehicle exploded in a garage 50 metres from the Sayyida Zeinab shrine.
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There was "substantial damage in the area of the blast," and "the terrorist who carried out the operation was killed," the agency said.
It was not immediately clear whether the bomber intended to target the shrine complex or a police station 15 metres away.
Car bombings and suicide bombings have become increasingly common as the 15-month uprising against Assad becomes militarised. Most have targeted security buildings and police buses.
The Syrian Observatory for Human Rights (SOHR), a UK-based opposition group, reported widespread raids by troops later in the capital.
The group said a car bomb in Idlib city targeted a military checkpoint, killing and wounding a number of soldiers.
Observers reach al-Haffa
From the day's early hours, Syrian troops bombarded rebel-held areas with tanks, mortars and helicopters in the central town of Rastan, the Damascus suburb of Douma, the central city of Homs and the northern towns of Anadan and Hreitan, near the Turkish border, the activists said.
Two opposition fighters, including Ahmed Bahbouh - head of the rebel military office in Rastan and a leading dissident - were reportedly killed at the edge of Rastan, which government forces have been trying to overrun for months.
UN observers find 'ghost town' as they reach al-Haffa
Troops bombarded Rastan "using helicopters and mortars, killing and wounding a large number of rebel fighters," the SOHR said.
The observatory accused UN observers in Syria of "silence," saying that they "do not move until after a city is defeated by regime troops, as happened in al-Haffa".
That was a reference to a town in Latakia province that was bombarded for eight days before troops moved in.
Monitors reached the town on Thursday, and found the main hospital burned, state buildings and an office of the ruling Baath party in ruins and a corpse lying in the street.
"A strong stench of dead bodies was in the air," said Sausan Ghosheh, spokeswoman for the UN observers.
She said there was still fighting in some pockets of the mountainous town in the seaside province of Latakia.
The number of casualties was unclear, Ghosheh said, and it appeared likely that, as in the past, bodies had been removed or buried before the UN mission got in.
'Crimes against humanity'
Amnesty International published a report on Wednesday, saying that Syria is committing crimes against humanity as part of state policy to exact revenge against communities suspected of supporting the opposition fighters.
The London-based rights group called for an international response after claiming it had fresh evidence that victims, including children, had been dragged from their homes and shot dead by soldiers, who in some cases then set the remains on fire.
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"This disturbing new evidence of an organised pattern of grave abuses highlights the pressing need for decisive international action," said Amnesty's Donatella Rovera following the release of the 70-page report entitled "Deadly Reprisals."
The group interviewed people in 23 towns and villages across Syria and concluded that government forces and armed groups were guilty of "grave human rights violations and serious violations of international humanitarian law amounting to crimes against humanity and war crimes".
Reporting on the revolt which broke out in March last year, Amnesty described how soldiers and shabiha militias, backing the regime, burned down homes and properties and fired indiscriminately into residential areas, killing and injuring civilian bystanders.
The report also accused the government of routinely torturing those who were arrested, including the sick and elderly.
In the report, Amnesty called on the UN Security Council to refer the case to the Prosecutor of the International Criminal Court, and to impose an arms embargo on Syria.