Releads; adds Syrian military's denial, grafs 11-15 (first version posted at 17:55)
At least 23 people were killed Sunday when the Syrian army attacked the Mediterranean port city of Latakia, activists said, with warships and tanks joining what they described as "a savage attack", dpa reported.
The London-based Syrian Observatory for Human Rights said 23 people were killed and dozens injured, several of them seriously.
A Palestinian source in Beirut told the German Press Agency dpa that the shelling had targeted a Palestinian refugee camp in Latakia's southern district of al-Ramleh.
"Several Palestinians were killed or wounded in al-Ramleh," said the Palestinian, who requested not be named.
"There is a mass exodus from al-Ramleh and the nearby area ... especially women and children," he added.
It was the first time the navy had joined in quelling protest areas, the Syrian Observatory for Human Rights said.
Snipers were firing from the tops of buildings in al-Ramleh and armoured vehicles had encircled the district, the observatory added.
Activists quoted by the broadcaster Al Arabiya said they had heard large explosions in Latakia's adjacent neighbourhoods of al-Ramleh and Masbah al-Shaab on Sunday.
Al-Ramleh has been the scene of protests against the government of Syrian President Bashar al-Assad since March.
The Local Coordination Committees of Syria, an opposition monitoring group, said the rail service to and from Latakia had stopped on Sunday.
Meanwhile, state Syrian news agency SANA quoted a military source as saying that two army soldiers had been killed in clashes with armed groups in al-Ramleh.
The source denied reports that warships were used in the military operation in Latakia.
On Sunday, Syria's human rights groups urged the authorities to release the head of the Syrian League for the Defence of Human Rights, Abdul Karim Rihawi, who was arrested on Thursday in Damascus.
His detention "represents a violation of the international commitments undertaken by Syria," they said in a joint statement.
"Security forces are continuing mass arrests, in violation of the law, human rights and democratic freedoms," the groups added.
Activists said that military and security forces had stormed on Sunday the suburban districts of Saqba and Hamouria in the capital Damascus and made mass arrests.
Mourners in Darayya near Damascus were shot at and besieged in a cemetery, Al-Arabiya TV reported, quoting an activist.
In a separate incident, a boy was killed in the central city of Hama when security forces fired on a mosque, according to the Federation of the Coordination Committees of the Syrian Revolution.
At least 11 civilians were killed Saturday in a series of army actions in Latakia, Hama and the central region of Homs, activists said.
Footage posted on the internet showed what activists described as overnight anti-government protests in several areas including Damascus, the north-eastern city of Deir al-Zour and Daraa in the south.
At least 1,790 civilians and 410 security personnel have been killed since pro-democracy protests began in Syria in mid-March, according to the Syrian Observatory for Human Rights.
It is hard to verify these reports, as the Syrian authorities have barred most foreign media and international human rights groups from the country.