A string of bombings, including a suicide attack claimed by the Islamic State group, struck in and around several Syrian cities on Monday, killing at least 43 people, mainly in government-controlled areas.

The SANA news agency reported blasts around the coastal city of Tartus, the central city of Homs, the suburbs of the capital Damascus, and the northeastern city of Hasakeh. The attacks were timed closely together, but authorities have not determined whether they were linked. ISIS claimed responsibility for the blast in Hasakeh.

Areas controlled by President Bashar Assad's forces have seen several bombings and other attacks during the country's five-year civil war, with many claimed by Al Qaeda-linked militant groups.

One of Monday's attacks took place in the heavily guarded suburb of Sabbourah, marking a major security breach. SANA said the attack killed one person, while the opposition-run Syrian Observatory for Human Rights said three people were killed.

"It's an area that houses officers and their families. Even before the revolution it was carefully guarded," said opposition media activist Yousef al-Boustani, referring to the 2011 uprising against Assad, which began with peaceful protests demanding reform.

The Britain-based Observatory, which maintains a network of contacts inside Syria, put the overall death toll at 47. Conflicting casualty figures are common in the Syria war.

Attackers detonated two bombs along the international coastal highway to the government stronghold of Tartus, SANA said, killing 35. A car bomb at the Arzoneh bridge was followed by a suicide bomber, who targeted a crowd that was gathering. The city, a stronghold of support for President Bashar Assad, is home to a major Russian naval base.

The Observatory said the twin blasts killed 35 people, including an army colonel, and wounded dozens more.

A survivor at the al-Bassel Hospital told state TV the blasts occurred near a checkpoint on the highway.

"My car caught fire and army soldiers pulled us out of the car," he said.

The governor of Homs province said a car bomb struck a military checkpoint in the provincial capital, killing three soldiers and a civilian, and wounding 10 others. The city of Homs, Syria's third largest, is largely under government control, with only one neighborhood still held by rebels. Monday's bomb exploded in the government-held Bab Tadmor district, SANA said. The Observatory said four soldiers were killed.

Syrian TV aired footage showing massive damage to the area, with a number of smashed cars and the bloodied body of a guard at the checkpoint.

An Islamic State attacker on a motorcycle blew himself up in the northeastern city of Hasakeh, killing eight, SANA said. Government forces withdrew in August after street battles with Kurdish forces, which took control of the city, though the state's police force remained in place.

The Observatory said the blast killed three members of the Kurdish police force, the Asayesh, and two civilians.

Except for the Hasakeh attack, there has been no immediate claim of responsibility for the blasts. The Islamic State group claimed twin suicide bombings in the neighboring coastal towns of Tartus and Jableh in May that killed over 160 people.