By Khaled Yacoub Oweis

AMMAN (Reuters) - Syrian forces hunted for insurgents in the central region of Homs Monday to crush armed resistance that is emerging after six months of protests against President Bashar al-Assad's rule.

The crackdown came a day after Syrian opposition groups meeting in Istanbul urged international action to stop what they called indiscriminate killings of civilians by the authorities.

Local activists said a military operation was now focused on Talbiseh near Homs, 94 miles north of Damascus, after security forces entered the nearby town of Rastan, which lies on the highway between the capital and the northern city of Aleppo.

For about a week, tank- and helicopter-backed troops had battled insurgents and army deserters in Rastan, in the most sustained fighting since Syria's uprising began in March.

The official Syrian news agency said Saturday government forces had regained control of the town.

"Tank fire targeted Talbiseh this morning and communications remain cut. The town was key in supplying Rastan and now it is being punished for that," one activist said. "House to house arrests are continuing in the area for the second day."

Armed insurgents, mostly in the central Homs region and the northwestern province of Idlib, have been so far outgunned.

While some Assad opponents have taken up arms, others are still staging demonstrations against his 11-year rule. Night protests erupted Sunday in several districts of Homs, where a crowd in the Khalidiya district shouted, "Homs is free."

A surge in sectarian killings has cast a pall of fear over the city. The state news agency said "armed terrorist groups" killed five people there Monday. Residents said two bodies had turned up in the city's Sunni Qarabid neighborhood.

Homs has a mixed population, with a few Alawite neighborhoods inhabited by members of Assad's minority sect, alongside others populated by majority Sunni Muslims.

MUFTI'S SON ASSASSINATED

Underlining the turn toward violence, the authorities said Sariya Hassoun, the son of Mufti Ahmad Hassoun, Syria's state-appointed top cleric, was assassinated in Idlib Sunday.

It was the first attack on the state-backed Sunni clergy who have backed Assad for decades, despite widespread Sunni resentment at Alawite dominance.

As Syria's struggle has grown bloodier, claiming at least 2,700 lives so far, according to a U.N. count, demonstrators have begun to demand some form of international protection that stops short of Libya-style Western military intervention.

Assad, 46, who succeeded his father in 2000, blames the violence on foreign-backed armed gangs. His officials say 700 police and soldiers have died, as well as 700 "mutineers."

A statement issued in Istanbul Sunday by a newly formed opposition National Council rejected intervention that "compromises Syria's sovereignty," but said the outside world had a humanitarian obligation to protect the Syrian people.

"The Council demands that international governments and organizations meet their responsibility to support the Syrian people, protect them and stop the crimes and gross human rights violations being committed by the current illegitimate regime."

The council said the uprising must remain peaceful but that military assaults, torture and mass arrests were driving Syria "to the edge of civil war and inviting foreign interference."

It also said the Muslim Brotherhood, the Damascus Declaration -- which groups established opposition figures -- and grassroots activists had all joined the Council.

The Istanbul meeting was a show of unity from a Syrian opposition that has shown little cohesion in six months of mostly peaceful protests against 41 years of Assad family rule.

"The fact that Islamists, secular figures and activists on the ground are now on one council is significant," a diplomat in Damascus said.

"But they still have to demonstrate they can be politically savvy and able to fill any political vacuum. They need a detailed action plan beyond the generalities of wanting a democratic Syria."

The government has dismissed opposition gatherings outside Syria as a foreign conspiracy to sow sectarian strife.

The Istanbul declaration was read out by Burhan Ghalioun, a secular academic living in France. He was flanked by Muslim Brotherhood leader Mohammad Riad al-Shaqfa as well as Christian and Kurdish politicians and several longstanding Assad critics.

France has publicly supported the National Council, but it has not yet won endorsement from the United States or from Syria's powerful neighbor Turkey, which has been enraged by what it describes as brutal killings of Syrian civilians.

Assad has relied on Russia and China, which have major oil concessions in Syria and do not want to see Western influence in the Middle East spread, to block any U.N. sanctions on Damascus.

European members of the U.N. Security Council are trying to persuade Russia to accept a watered-down resolution that would threaten "targeted measures" against Damascus if it fails to end its crackdown on pro-democracy demonstrators, without explicitly threatening U.N. sanctions, Council diplomats said.

European envoys say that they hope the Council will vote on the Syria resolution Tuesday.

(Writing by Khaled Yacoub Oweis, Amman newsroom; Editing by Alistair Lyon)