Syrian government forces 'shell rebel-held towns'
Security forces have been shelling rebel-held towns in Syria, activists say, as President Bashar al-Assad vowed to continue fighting "terrorism".
A boy and five soldiers were reportedly killed as troops launched an assault on the southern town of Herak, a base of the Free Syrian Army (FSA).
Activists also said 23 people had died in Homs, five days after the FSA pulled out of the city's Baba Amr district.
A new UN Security Council resolution is meanwhile reportedly being discussed.
The US proposed demanding an end to the violence, first by Syrian government forces and then by armed rebels, the Associated Press said.
The five permanent members of the Security Council, plus Morocco - the Arab representative - are to discuss it behind closed doors on Tuesday.
Russia and China have vetoed two previous resolutions, saying they were unbalanced and only demanded the government stop attacks.
The Russian foreign ministry said earlier that, contrary to reports in US and European media, its position on Syria had not changed because Prime Minister Vladimir Putin had won Sunday's presidential election.
"We would like to urge our American and European partners not to engage in wishful thinking. The Russian position on the Syrian settlement has never been affected by opportunistic considerations and is not formed under the influence of electoral cycles," a statement said.
US President Barack Obama later said the situation in Syria was "heartbreaking", but that there was no "simple solution".
"On the other hand, for us to take military action, unilaterally, as some have suggested, or to think that somehow there's some simple solution, I think is a mistake," Mr Obama said.
As the international community remained divided on how to end the violence, which the UN says has left more than 7,500 people dead in the past 12 months, deadly clashes were reported across Syria on Tuesday.
The bombardment of Herak, a town in Deraa province, began in the morning and triggered "very intense" fighting between security forces and a large number of FSA fighters holed up inside, the head of the UK-based Syrian Observatory for Human Rights, Rami Abdul Rahman, told AP.
Explosions shook the town as shells reportedly hit residential areas and mosques, where armed defectors were believed to be sheltering.
A video posted online showed what activists said was the inside of the Abu Bakr al-Saddiq mosque in Herak. It was littered with rubble, while its doors had been blown off and its windows shattered. A man on camera said a tank fired at the building after residents sought refuge inside.
Mr Abdul Rahman said the rebels had ambushed an armoured personnel carrier, killing five soldiers and wounding several others.
He and the Local Co-ordination Committees (LCC), another activist group, said a 15-year-old boy had also been killed by snipers.
The LCC said 35 people had been killed by security forces across Syria on Tuesday. Twenty-three people had died in Homs, it added, including 13 members of two families, who were allegedly killed with knives by security forces personnel and pro-government militiamen in Baba Amr.
The private TV station al-Dunya, which is very close to the Syrian government, meanwhile broadcast video which it said showed the massacre of an entire extended family of 16 or 17 people - ranging from a one-year-old child to an 85-year-old man - who had allegedly been killed in their home in Baba Amr by men armed with knives.
Al-Dunya said it was the work of "armed terrorist gangs", who are blamed by the government in Damascus for all the trouble in the country. But activists said the slaughter was the work of security forces, and named all the victims as "martyrs" of the revolution against President Assad.
The International Committee of the Red Cross (ICRC) and the Syrian Red Crescent are still being prevented from entering the district to deliver aid and evacuate the wounded on the grounds that it is too dangerous.
But meanwhile a big clean-up operation has got under way there, shown by Syrian state TV. The state news agency said residents were returning because the authorities had "restored stability and security".
President Assad said the Syrian people had "again proven their capacity to defend the nation and to build a new Syria through their determination to pursue reforms along with the fight against foreign-backed terrorism".
The UN refugee agency (UNHCR) has said, however, that more than 1,500 people, mostly women and children from in and around Homs, have crossed the border with neighbouring Lebanon to escape the violence.
Spokeswoman Dana Suleiman told the AFP news agency that 170 families - each comprising about six or seven people - had sought refuge in the village of al-Fakha and 50 others in the nearby town of Arsal.
Earlier, the Syrian Observatory for Human Rights reported that Syrian forces had shelled a bridge over the Orontes river at the village of Rabla which was being used by refugees to reach Lebanon.
Turkey's Prime Minister Recep Tayyip Erdogan urged Syria to allow the opening of humanitarian corridors to get relief supplies to civilians.
"Humanitarian aid corridors to Syria must be opened right away and we must heap pressure on the Syrian administration to deliver humanitarian aid to the Syrian people, especially to Homs," he told parliament.
"The Arab League decision on Syria must be implemented without wasting any more time," he added, referring to its demand that Mr Assad hand over power to his deputy immediately - something he has rejected.
The UN's Under-Secretary-General for Humanitarian Affairs, Valerie Amos, is to arrive in Damascus on Wednesday. She said her aim was to "urge all sides to allow unhindered access for humanitarian relief workers so they can evacuate the wounded and deliver essential supplies".
However, the BBC's Jim Muir in Beirut says that with the Syrian government apparently bent on crushing resistance wherever it finds it, her chances of achieving anything significant appear slight.