BEIRUT -- Government troops backed by allied militiamen have stormed a predominantly Sunni village in central Syria killing at least 15 people, while opposition forces began an offensive near Aleppo to try to cut the army's supply route to the northern city, activists said Saturday.

The Britain-based Syrian Observatory for Human Rights said the attack on the village of Sheik Hadid occurred late Friday and that the dead included two women and a child. It said the rest were men but did not know if they included rebel fighters.

The Local Coordination Committees, another activist group, said 26 people were killed in Sheik Hadid, including some who were killed with knives. Rami Abdul-Rahman, who heads the Observatory, said at least two of the dead were stabbed to death.

The discrepancy in numbers could not be immediately reconciled.

The assault came shortly after rebels captured Jalma, another village close to Sheik Hadid in Hama province, killing five soldiers. The Observatory said fighting raged Saturday in Sheik Hadid and nearby areas.

The civil war, which has left more than 100,000 dead, has taken increasingly sectarian overtones. Most of the rebels trying to overthrow President Bashar Assad belong to the majority Sunni sect while his regime is dominated by members of his minority Alawite sect, an offshoot of Shiite Islam.

The Observatory also reported clashes between fighters of two hard-line rebel organizations, al-Qaida's Islamic State in Iraq and the Levant and the Nusra Front, against Kurdish gunmen in the northern province of Raqqa. The group says 17 hard-liners and three Kurdish gunmen have been killed in the fighting since Friday.

Clashes between Islamic militants and Kurdish gunmen over the past months in northern Syria have left hundreds dead.

Also in northern Syria, the Observatory said the rebels launched a wide offensive south of Aleppo, Syria's largest city, in an attempt to cut supplies to government forces in the contested metropolis.

The Observatory said rebels captured six villages south of Aleppo amid heavy fighting. It had on word on casualties.

Rebels control large parts of northern Syria and some neighbourhoods of Aleppo, once Syria's commercial capital.

Meanwhile, Syria's main opposition group rejected an offer by Iran's new president, Hasan Rouhani, to help in holding a national dialogue to end the Arab country's crisis.

The Syrian National Coalition's statement came two days after Rouhani wrote in the Washington Post that Tehran was ready to facilitate talks between Assad's government and the opposition.

Iran has been one of Assad's strongest backers and is believed to have sent the Syrian government weapons and billions of dollars since the crisis began in March 2011. Lebanon's Iranian-backed Hezbollah group has fought alongside Assad's forces.

"The Iranian statement is ridiculous after all the blood that Iran participated in shedding ... through its political, economic and military support to Assad," said the SNC statement.

"It is better if the Iranian leadership withdraws its military experts and fanatic fighters from Syria before coming with initiatives for the concerned parties. It (Iran) is part of the problem," the statement said.