The Syrian military is reportedly moving deeper into residential areas in the city of Homs, a day after the Russian foreign minister said President Bashar al-Assad was "fully committed" to ending the bloodshed.
Activists said the army was firing rockets and mortar rounds to subdue opposition districts on Wednesday, as tanks entered the Inshaat neighbourhood and moved closer to Bab Amr.
An activist in Bab Amr told Al Jazeera that the neighbourhood had been under fire for several days.
The army is "shelling us, using rockets, using mortars, using Russian tanks", he said. "Tanks are trying to break into the neighbourhood of Bab Amr."
Activist Hadi al-Abdallah said that at least 43 people were killed overnight in the central city, and other activists reported even higher death tolls.
“Some areas are completely [besieged]. There is no internet, no landlines or mobile lines," Al-Abdallah said.
He said there had been no retaliation by the armed opposition because the government forces were shelling from positions several kilometres away.
As the shelling of Homs continued for the fifth straight day, Ahmet Davutoglu, the Turkish foreign minister, announced plans for an international meeting to forge a common approach between regional players and world powers to the Syrian crisis.
"We are determined to establish a broad-based forum to promote international understanding with all countries concerned" with developments in Syria, Davutoglu said in a televised interview on Wednesday.
The conference could take place in Turkey or in another country but it must certainly be "in the region" and "as soon as possible", he said.
Earlier, Navi Pillay, the UN rights chief, issued an appeal for urgent international action to protect civilians.
"I am appalled by the Syrian government's wilful assault on Homs, and its use of artillery and other heavy weaponry in what appear to be indiscriminate attacks on civilian areas in the city," a statement from the Office of the UN High Commissioner for Human Rights said.
View Homs - Recent developments in a larger map to read about the neighbourhoods affected by the ongoing military campaign
"The failure of the Security Council to agree on firm collective action appears to have fuelled the Syrian government's readiness to massacre its own people in an effort to crush dissent."
The Syrian Revolution General Commission, a coalition of 40 Syrian opposition groups, said that 2,814 people had been killed in Homs since the beginning of the uprising.
Mohammad Hassan, another activist in Homs, said bombardment had intensified in the early morning of Wednesday, targeting Bab Amr, al-Bayada, Khalidiyeh and Wadi al-Arab, all which have revolted against Assad.
"Mortar and rocket fire has subsided, but heavy machineguns and anti-aircraft guns are still strong," he said. "Tanks are in main thoroughfares in the city and appear poised to push deep into residential areas."
State media reported that "armed terrorist groups" had attacked police roadblocks in Homs and fired mortar bombs at the city, with three falling on the Homs oil refinery.
"Armed terrorist groups shelled the refinery in Homs, setting two fuel depots on fire," Syrian television said.
The opposing claims came as Sergei Lavrov, the Russian foreign minister, returned to Moscow after holding talks with Assad in Damascus a day earlier.
Lavrov said Syrians themselves should decide the fate of their leader.
"Any outcome of national dialogue should become the result of agreement between the Syrians themselves and should be acceptable to all the Syrians," he said in Moscow.
Both sides blamed
Lavrov blamed both the Damascus leadership and opposition forces for instigating the violence that activists say has killed more than 7,000 people since March.
He said that "on both sides there are people that aim at an armed confrontation, not a dialogue".
Assad had told Lavrov that Syria was determined to hold a national dialogue with the opposition and independent figures, saying his government was "ready to co-operate with any effort that boosts stability in Syria", according to the official SANA news agency.
| Al Jazeera exclusive: Jane Ferguson reports on military campaign in the city of Homs
Lavrov said Assad had "delegated the responsibility of holding such a dialogue to Vice-President [Farouk] al-Sharaa".
Repeated efforts by the Arab League and Russia to broker talks have been rejected by the Syrian opposition, which refuses any negotiations while the crackdown continues.
Russia - which government wields unique leverage as a major arms supplier with longstanding political ties to Syria, and a naval facility on its coast - vetoed a UN Security Council on Syria along with China last week.
Walid al-Bunni, a senior member of the opposition Syrian National Council, said Lavrov had brought no new initiative and that "so-called reforms" promised by Assad were not enough.
"The crimes that have been committed have left no room for Bashar al-Assad to remain ruler of Syria," he told the Reuters news agency.
In the latest diplomatic developments, Gulf Arab states joined the US and several European countries in withdrawing their ambassadors from Damascus on Tuesday.