Government forces intensified fighting Saturday inside Syria's Eastern Ghouta, as tens of thousands of civilians in the besieged rebel enclave east of Damascus awaited urgently needed aid.
On another front in Syria's seven-year civil war, Turkish air strikes killed 36 pro-regime fighters in a Kurdish enclave near the Turkish border.
Syria's war has killed more than 340,000 people and spiralled into a complex conflict involving world powers since starting in 2011 with the brutal repression of anti-government protests.
Russia-backed regime forces have since February 18 killed more than 640 civilians -- including over 150 children -- in bombardment of Eastern Ghouta, one of the armed opposition's last strongholds in the country.
Following a deadly wave of air strikes and shelling, fighting on the ground has intensified in recent days, with loyalists retaking several areas inside the agricultural region, the Syrian Observatory for Human Rights said.
Regime forces have advanced steadily since Thursday, the Britain-based monitor said, recapturing two areas in the east and southeast of the enclave on Saturday alone.
"Regime forces and their allies have intensified their attacks on rebel positions in the past 48 hours," Observatory head Rami Abdel Rahman said.
Eastern Ghouta's 400,000 residents have lived under regime siege since 2013, facing severe food and medicine shortages even before the latest offensive.
- 'Scorched earth policy' -
The fighting on the ground comes after Russia on Tuesday started a daily five-hour "humanitarian pause" in the enclave -- a move that falls far short of a 30-day ceasefire demanded by the UN Security Council.
The ferocity of the bombardment initially lessened but it has continued to claim lives, and trucks loaded with desperately needed aid remain unable to enter the enclave.
Thousands of civilians instead are surviving on meagre stocks, and medical staff struggle to treat casualties with inadequate medical supplies.
The UN Human Rights Council postponed voting Friday on a British resolution condemning the crisis in Eastern Ghouta, after member states failed to agree on a final text.
Moscow has offered safe passage to non-combatants wishing to leave the enclave during the pause, but no Syrian civilians have left since Tuesday, the Observatory says.
Government fighters are trying to advance inside Eastern Ghouta to cut off the main town of Douma and its surroundings in the north of the enclave, as well as isolate the southeastern area of Al-Marj, Abdel Rahman said.
Jaish al-Islam, a main opposition group in the region, accused regime forces of carrying out a "scorched earth policy" as they progressed into the enclave.
Opposition fighters abandoned their positions confronted with "hysterical bombing" in agricultural areas in the east, Jaish al-Islam spokesman Hamza Bayraqdar said on Telegram.
- Deadly Turkish strikes -
In the northwest of the country, there was more bloodshed in the roughly six-week offensive by Turkey and allied fighters against Kurdish militia now backed up by pro-government Syrian forces.
Turkish air strikes killed at least 36 pro-regime fighters battling alongside the Kurds in the enclave of Afrin on Saturday, the Observatory said.
The Kurdish-led Syrian Democratic Forces (SDF) alliance said the Turkish raids targeted pro-regime positions, but gave no death toll.
The two-storey building where the fighters were located was completely eviscerated, an AFP correspondent reported, with several burnt out vehicles visible among the rubble.
The Observatory said the strikes on the area of Kafr Janna were the third such raid on loyalist fighters in the enclave bordering Turkey in less than 48 hours.
They came after Turkish raids on other parts of the enclave killed 14 pro-regime fighters on Thursday and four more on Friday, the monitor said.
Turkish-led Syrian opposition fighters on January 20 launched an assault on Afrin, controlled by the Kurdish People's Protection Units (YPG).
Pro-regime fighters joined the Kurdish militia inside the enclave a month later, after the Kurds appealed to Damascus for help.
The Observatory says Turkish-led forces control more than 20 percent of the enclave after seizing the area of Rajo in the northwest of Afrin on Saturday.
They also seized a strategic mountain in the northeast of the enclave, a military official from the Turkish-led operation said.
Ankara says the YPG is a "terrorist" extension of the Kurdistan Workers' Party (PKK), which has waged a three-decade insurgency against the Turkish state.
The YPG has been a key component of a US-backed SDF, a Kurdish-Arab alliance that has been fighting the Islamic State jihadist group in Syria.
The Observatory says more than 140 civilians have been killed in Turkish bombardment since the start of the assault, but Turkey denies the claim and says it takes the "utmost care" to avoid civilian casualties.
Thousands of civilians have fled their homes since the start of the operation, either to the town of Afrin or to nearby government-controlled areas.