Initial reports said 20 police were killed in an ambush by "armed gangs". But officials later said dozens more had died in other incidents, including 82 in an attack on their headquarters.
If confirmed, it would be the deadliest day for the security forces since anti-government protests began in mid-March.
A witness has cast doubt on the claims.
Foreign media are greatly restricted in Syria and these reports have not been independently verified.
'A genuine massacre'
The state media reports came a day after human rights activists said at least 35 people, including police, had been killed in Jisr al-Shughour, close to the Turkish border.
Syrian Interior Minister Ibrahim Shaar said the government would respond "strongly and decisively" to Monday's reported attacks.
State TV said hundreds of armed gunmen had taken over parts of Jisr al-Shughour, about 20km (12 miles) from the Turkish border, attacking government buildings and setting them on fire.
It said gangs using light weapons, grenades and stolen explosives ambushed police as they approached the town early on Monday, killing 20 officers.
The police convoy had been "on their way to rescue citizens being terrorised" by the gangs in Jisr al-Shughour, said the report.
Another 37 security officials were killed in an attack on the town's security centre and eight in a bomb attack on a post office, while the bloodiest incident occurred when gunmen took over the security services' headquarters, it added.
"The armed groups in Jisr al-Shughour carried out a genuine massacre and mutilated some of the bodies," said the TV report.
The official Sana news agency quoted a correspondent as saying reinforcements had been sent to Jisr al-Shughour and that security forces personnel were surrounding houses from which armed men were firing weapons.
He added that the gunmen were using civilians as human shields, and that some of their victims' bodies had been thrown in the Orontes river.
'Shot in the back'
A witness told BBC Arabic that the protesters did not have weapons.
"We don't have any kind of weapons," he said. "The soldiers were coming our way, then they were shot in the back by some Syrian security elements."
Human rights activist Mustafa Osso also told the Associated Press he doubted the claims by officials, saying the protesters had so far been peaceful and unarmed.
The BBC's Jim Muir in Beirut says if official reports are correct, it would be the first time officials have admitted to such a large loss of personnel.
Our correspondent says there has been an unusual lack of information about the clashes on opposition websites and Facebook pages.
One protest site said Jisr al-Shughour had been surrounded and there were suggestions some members of the security forces had switched sides.
The unrest began in the southern city of Deraa before spreading.
Activists say more than 1,100 people have been killed in the unrest.
Mr Assad, whose family has been in power for four decades, has promised to introduce reforms, but this has done little to placate his opponents.
Source:
http://www.bbc.co.uk/news/world-middle-east-13672725
