Iran said yesterday that its support for Syria was "unchangeable" despite mounting international pressure on the country's president, Bashar Al Assad, to step down.
Comments from several top Iranian officials reinforced Tehran's backing for its main Middle East ally and countered speculation that Iran's leadership was facing internal battles over whether to change its approach to Mr Al Assad.
"The Iranian people have an unchangeable stance on Syrians and will always stand by them," Iran's Press TV quoted first Vice President Mohammad Reza Rahimi as saying.
The secretary of Iran's National Security Council, Saeed Jalili, said Tehran would back Damascus "more than before in the face of foreign pressure", the official IRNA news agency reported.
Despite lauding political upheaval in other Arab countries, Iran has dismissed the uprising against Mr Al Assad's rule as a foreign conspiracy.
Iran's vice president in charge of international affairs, Ali Saeedlou, described the two countries as powerful nations able to influence regional and global stability.
"Tehran is ready to give its experience and capabilities to its friend and brother nation of Syria," Mr Saeedlou said in a meeting with Syria's deputy prime minister, Omar Ghalawanji, who is in Tehran with a Syrian delegation.
Mr Saeedlou did not elaborate about which experience or capabilities he had in mind.
In a concrete sign of support for the Syrian regime, the delegation of Syrian ministers agreed a deal on importing Iranian electricity via Iraq.
In Syria itself, the battle for Aleppo continued yesterday as troops and rebels prepared for a head-on confrontation. Pro-regime media warned of a looming "mother of all battles".
"The army's reinforcements have arrived in Aleppo," said Colonel Abdel Jabbar Al Okaidi, a spokesman for the rebel Free Syrian Army.
"We expect a major offensive at any time, specifically on areas across the southern belt, from east to west."
Mr Okaidi added that 100 regime tanks and a large number of military vehicles had arrived in Aleppo.
The US state department said that credible reports of tank columns moving on Aleppo along with air strikes by helicopters and planes represented a "serious escalation" of the government's efforts to crush the rebellion.
"This is the concern: that we will see a massacre in Aleppo and that's what the regime appears to be lining up for," the state department spokeswoman Victoria Nuland said.
"Our hearts are with the people of Aleppo, and again this is another desperate attempt by a regime that is going down to maintain control, and we are greatly concerned about what they are capable of in Aleppo."
Intermittent clashes were also reported in southern Damascus, with seven people killed there and 16 others, including five children, killed in shelling on Yalda village just south of the capital, the Syrian Observatory for Human Rights said yesterday.
Across Syria, at least 114 people were killed yesterday, including 61 civilians, 32 regime troops and 21 rebels, said the Observatory.
With the violence showing no signs of abating, the Obama administration is weighing its options for more direct involvement if the rebels can wrest enough control to create a safe haven for themselves.
US secretary of state Hillary Clinton says it is only a matter of time before the rebels have enough territory to create such areas.
"More and more territory is being taken," Mrs Clinton said this week. "It will eventually result in a safe haven inside Syria, which will then provide a base for further actions by the opposition."
The Turkish prime minister Recep Tayyip Erdogan said on yesterday that Turkey could act against a "terrorist" organisation in northern Syria if it sees it as a threat, in a warning to Kurdish militants believed to be active in the region.
"We will not allow a terrorist group to establish camps in northern Syria and threaten Turkey," Mr Erdogan told a news conference before travelling to London. "If there is a step which needs to be taken against the terrorist group, we will definitely take this step," he said.
His comments were Ankara's first acknowledgement of concern about the growing influence of Syria's Democratic Union Party - linked to the Kurdistan Workers Party that has fought a 28-year separatist conflict in Turkey.
Israel increased security yesterday along its ceasefire line with Syria in the occupied Golan Heights.
With the clashes spreading across the Syrian side of the strategic plateau, Israeli troops were put on "very high" alert.
Without giving numbers,an Israeli source said a large number of soldiers had been transferred to the plateau to be on hand if the situation took a turn for the worse.
The most prominent defector from the regime said yesterday he would "help as much as I can to unite all the honourable people inside and outside Syria to put together a road map to get us out of this crisis, whether there is a role for me or not".
Brig Gen Manaf Tlass, a commander in the powerful Republican Guard and the son of a former defence minister who was the most trusted lieutenant of the president's father, defected this month and flew to Paris.
He is now in Saudi Arabia, a key financial backer of the rebellion. Mr Tlass he told Al-Sharq Al-Awsat that he does not see a future for Syria with his former friend at the helm.
But a meeting in Rome yesterday offered further evidence of the fractured nature of Syrian opposition groups. Dissidents signed a joint appeal for a political solution to the conflict, calling for a ceasefire, the release of detainees and national reconciliation.
"We cannot accept Syria being transformed into a theatre of regional and international conflict," said the 17 signatories of the appeal, including leaders of the National Coordination Body and the Democratic Forum.
The main exiled opposition group, the Syrian National Council, was excluded because "they are calling for violence", according to the charity.
*Reporting by Reuters, Associated Press, Agence France-Presse