DAMASCUS (AFP) - Separate bomb attacks claimed by the Islamic State in Iraq and Syria (ISIS) killed at least 119 people as Washington pursued efforts for a ceasefire.
As US Secretary of State John Kerry said a provisional deal had been reached on the terms of a truce, violence intensified on the ground on Sunday (Feb 21).
Double car bombings killed at least 57 people and wounded dozens in the Al-Zahraa district of the central city of Homs, the Britain-based Syrian Observatory for Human Rights monitor said.
And near Damascus, a series of bomb attacks, including a car bombing, ripped through the area of the Sayyida Zeinab Shiite shrine and killed 62 people, the monitor said.
The militant ISIS said it was behind the carnage.
State television footage from Homs showed emergency workers carrying a charred body on a stretcher past devastated shops and mangled cars and minibuses.
The attack was the worst since twin blasts in October 2014 hit a school, killing at least 55 people, including 49 children.
Al-Zahraa - whose residents are mostly from the same Alawite sect as Syria's ruling clan - has been regularly targeted.
ISIS, which last month claimed a double bombing that killed 22 people, said it carried out the latest attack.
Two militants drove explosive-laden cars into crowds of residents, it said in an online statement.
The group also said two of its suicide bombers carried out the Sayyida Zeinab bombings.
State television said a car bombing and two suicide attacks hit the area, killing 30 and wounding dozens, whereas the Observatory gave a death toll of 62 in four attacks.
ISIS was also behind a massive attack in January that killed 70 people near the shrine, which contains the grave of a granddaughter of the Prophet Mohammed and is revered by Shiites.
World powers have been pushing for a halt in fighting in Syria that was meant to take effect by Friday, but have struggled to agree on the terms.
The latest bombings came as Mr Kerry said he had spoken with his Russian counterpart Sergei Lavrov and agreed on how to implement a ceasefire.
"We have reached a provisional agreement, in principle, on the terms of the cessation of hostilities that could begin in the coming days," Mr Kerry said in Amman.
"It is not yet done and I anticipate that our presidents, President (Barack) Obama and President (Vladimir) Putin, may well speak somewhere in the next days or so in order to try to complete this task."
World powers proposed the truce just over a week ago as part of a plan that also included expanded humanitarian access, in a bid to pave the way for peace talks to resume.
The talks, which collapsed earlier this month in Geneva, had been scheduled to resume on Feb 25, but the UN's Syria envoy has already acknowledged that date is no longer realistic.
On Saturday, key opposition umbrella group, the High Negotiations Committee (HNC), said it would agree on a temporary truce only if regime backers halted fire.
HNC chief Riad Hijab said any ceasefire must be reached "with international mediation and with guarantees obliging Russia, Iran and their sectarian militias and mercenaries to stop fighting".
Mr Assad, meanwhile, told Spain's El Pais newspaper he was "ready" for a ceasefire, but said it should not be exploited by "terrorists".
Regime backer Moscow is a key architect of the proposed ceasefire, but has shown little sign so far that it plans to rein in the air campaign it began in September in support of Mr Assad's government.
On Saturday, the Kremlin said it would continue "to provide assistance and help to the armed forces of Syria in their offensive actions against terrorists".
Regime forces backed by Russian strikes were advancing on Sunday east of Aleppo city against ISIS, consolidating their control over a stretch of highway from the city to the Kweyris military base.
The Observatory said at least 50 ISIS fighters had been killed in clashes and Russian strikes since Saturday morning.
Tensions have been rising between Moscow and opposition-backer Ankara, alarmed by both the regime's Russian-backed advances and a major operation by Kurdish-led forces in Aleppo province.
The Kurdish People's Protection Units (YPG) and their Arab partners have in recent days seized key territory from rebel forces in Aleppo, prompting Turkey to shell their positions.
Ankara considers the YPG to be an affiliate of the outlawed Kurdistan Workers' Party, which has waged a decades-long insurgency against the Turkish state.
It fears the Kurdish advances are intended to link up areas in north and north-east Syria to create a contiguous semi-autonomous Kurdish zone along the Syrian-Turkish border.
On Sunday, Turkish President Recep Tayyip Erdogan defended his country's fight against the YPG as "legitimate defence" after international calls for Ankara to halt its military action in Syria.
