by weedah Hamzah

Beirut (dpa) - The bombings on Damascus and Homs, claimed by Islamic State and targeting Syrian government-held territories, killed 184 people, in the largest single-day toll from such blasts, a monitoring group said Monday.

Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, told dpa that the Sunday attacks were the deadliest one-day bombings since the Syrian uprising erupted in 2011.

Islamic State and allied jihadist groups, meanwhile, attacked the sole supply route for the government to Aleppo city in the north, cutting off a key road near the town Khanasser to the south-east.

Aleppo, the second largest city in Syria, is divided between rebels in the east and regime forces on the western side. The government, backed by intense Russian airstrikes, is closing in on the rebels and experts predict the eastern part of the city could fall under a siege.

"Regime forces have launched a counterpart and are advancing to take the vital road back," Abdel Rahman told dpa.

"It is key for the regime to get back the road as it would slow their plans to advance to the rebel held areas of the city and impose a siege on the area," he added.

The Britain-based watchdog said 120 people, including 75 civilians, were killed Sunday after two suicide attacks and two car bombs rocked Sayeda Zeinab, a Shiite area south of the capital Damascus.

In Homs, the death toll stood at 64, among them 39 civilians, in the city's al-Zahara district, the Observatory said. The neighborhood's residents belong in large part to the Alawite sect of Syrian President Bashar al-Assad.

Statements in the name of the Islamic State movement, posted on social media, claimed responsibility for both attacks.

It is not possible to verify the claims but they were consistent with previous statements by the group, including claims of responsibility for three other deadly attacks in the same areas since December.

The attacks came as world powers discussed ways to implement a Syrian ceasefire in the coming weeks.

US Secretary of State John Kerry said Sunday that he had reached a "provisional agreement in principle" with Russian Foreign Minister Sergei Lavrov on terms for a truce.

In Saudi Arabia, members of the opposition's Higher Negotiations Committee told dpa they were due to meet Monday to discuss the proposed ceasefire after rebel representatives gave their "initial approval".

A cessation of hostilities by Friday was proposed on February 12 by world powers meeting in Munich, Germany. Part of the plan was also to ensure access for humanitarian aid to besieged areas in Syria. The UN says more aid has been entering blocked areas.