Syrian forces on Wednesday stormed a rebel bastion as UN chief Ban Ki-moon urged President Bashar al-Assad to "immediately" implement a six-point UN peace plan he reportedly accepted.
China and Russia also upped the pressure urging both their allySyria and the opposition to honour commitments to halt armed conflict, which has claimed thousands of lives since it first erupted in March last year.
Moscow strongly urged the Syrian opposition to "follow the example" of the Damascus regime in supporting the mediation efforts of UN-Arab League envoy Kofi Annan to stop the bloodshed.
And in Baghdad, Arab foreign ministers thrashed out a resolution on Syria to be debated at a landmark Arab League summit on Thursday, even as Damascus warned it would not abide by any of its initiatives.
The Syrian Observatory for Human Rights said Syrian forces backed by tanks swept into the central Hama province town of Qalaat al-Madiq and nearby villages after dawn on Wednesday after a siege lasting more than two weeks.
"Heavy clashes between regime forces and armed rebels are preventing the army from advancing," the Britain-based monitoring group said. "Intense gunfire and explosions can be heard in nearby villages."
At least four civilians caught in the crossfire were killed while four soldiers and four rebels also died in the fighting, the Observatory said.
Qalaat al-Madiq, which the army has pounded for 17 straight days to root out rebels, is home to a historic castle that was shelled during the fighting, as seen in videos posted on YouTube.
Abu Ghazi, a local activist reached by Skype, told AFP in Beirut that members of the rebel Free Syrian Army had withdrawn from the area because of the regular army's superior firepower.
The offensive is part of the regime's efforts to overrun rebel strongholds as it tries to crush an unprecedented year-long revolt, which monitors say has killed almost 10,000 people. The UN say more than 9,000 have died.
Fierce clashes were also reported on Wednesday across the country, including in northwest Idlib province, central Homs and the southern province of Daraa, cradle of the year-long revolt, the Observatory said.
Political efforts to end the violence were in full gear on Wednesday as Arab foreign ministers prepared for the landmark summit in Iraq, which the UN chief was due to attend.
"I urge President al-Assad to put commitments into immediate effect. There is no time to waste," Ban said in Kuwait before travelling to Baghdad.
He expressed concern at the continued bloodshed but welcomed Syria's acceptance of a plan to end the violence put forward by Annan as an "important initial step" towards ending the bloodshed.
Ban said he would "meet key (Arab) leaders in Baghdad to discuss how the UN and Arab League states can work together in helping the joint special envoy's diplomatic efforts to get the six-point proposal implemented."
Annan said on Tuesday that Assad's government had accepted his plan, a move cautiously welcomed by Western nations.
The plan calls for a commitment to stop all armed violence, a daily two-hour humanitarian ceasefire and media access to all areas affected by the fighting in Syria.
The plan also calls for an inclusive Syrian-led political process, a right to demonstrate, and the release of people detained arbitrarily.
A copy of the draft resolution being debated by Arab foreign ministers in Baghdad urges the Syrian regime to "immediately stop all actions of violence and killing, protect Syrian civilians and guarantee the freedom of peaceful demonstrations for achieving demands of the Syrian people."
The text, obtained by AFP, also calls on the Syrian government and all opposition factions "to deal positively with the envoy (Annan) by starting serious national dialogue."
Arab League Secretary General Nabil al-Arabi said he expected Thursday's summit to support Annan's proposals.
But Syrian foreign ministry spokesman Jihad Makdissi said Damascus will reject any initiative stemming from the Arab summit. "Syria will not cooperate with any Arab League initiative at any level," he said.
"Since its suspension from the Arab League, Syria has been dealing with member states on a bilateral level," he told AFP.
The 22-member pan-Arab body in November voted at an extraordinary meeting to suspend Syria until Assad implements an Arab deal to end the crackdown on dissent.
Western powers cautiously welcomed the statement by Annan's camp that Assad had accepted his peace plan.
"Given Assad's history of over-promising and under-delivering, that commitment (to Annan) must now be matched by immediate actions," US Secretary of State Hillary Clinton said.
French foreign ministry spokesman Bernard Valero was likewise sceptic.
"The Istanbul meeting will be an opportunity for the international community to assess whether the regime in Damascus is applying this plan or not, respecting its commitments or not, and ending the massacres it has carried out daily for more than a year or not," he said.
On Sunday, the Friends of Syria will gather in Istanbul for their second meeting since February in a bid to end the crisis, with the United States, France and numerous Arab countries due to attend.
Russia and China, which are both boycotting the event, have triggered international fury for vetoing two UN Security Council resolutions on Syria.