The secretary-general of the United Nations has said that the Arab League intends to restart its controversial observer mission in Syria, and suggested that the world body could back a joint initiative.
Ban Ki-moon told reporters on Wednesday that the head of the Arab League had told him of the plan to revive the mission and had asked for it to become a joint operation with the UN.
The move came as Syrian forces continued a relentless assault on the city of Homs, reportedly killing scores of people.
Ban said he spoke to Nabil al-Arabi, the Arab League secretary-general, by telephone on Tuesday.
"He informed me that he intends to send the Arab League observer mission back to Syria and asked for UN help," Ban said.
"He further suggested that we consider a joint observer mission in Syria, including a joint special envoy."
The UN chief said consultations would be held with Security Council members in the coming days "before fleshing out the details".
Turkey earlier said it was planning an international conference of regional and world powers while the European Union threatened to impose harsher sanctions on Syria.
Amid the flurry of diplomatic activity, activists said the army was firing rockets and mortar rounds to subdue opposition districts, and 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."
Hadi al-Abdallah, an activist, said more than 50 people were killed overnight in the central city.
"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.
Turkish and EU moves
As the shelling of Homs continued for a fifth straight day, Ahmet Davutoglu, the Turkish foreign minister, announced plans for an international meeting.
"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.
View Homs - Recent developments in a larger map to read about the neighbourhoods affected by the ongoing military campaign
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.
A senior EU official in Brussels said the 27-nation bloc would soon impose harsher sanctions against Syria.
The official said the new measures could include bans on the import of Syrian phosphates, on commercial flights between Syria and Europe, and on financial transactions with the country's central bank. The European Union imports 40 per cent of Syria's phosphate exports.
The official, who spoke on condition of anonymity, said some measures would be adopted at the EU foreign ministers meeting on February 27.
But he stressed the nature of the measures to be adopted remained unclear since the ministers were concerned over the impact on the Syrian public.
Meanwhile, 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.
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 early on Wednesday, targeting Bab Amr, al-Bayada, Khalidiyeh and Wadi al-Arab, all of which have revolted against Assad.
"Mortar and rocket fire has subsided, but heavy machine-guns 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".
| Al Jazeera exclusive: Jane Ferguson reports on military campaign in the city of Homs
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.
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 initiate talks have been rejected by the Syrian opposition, which refuses any negotiations while the crackdown continues.
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.