Syrian forces shot dead at least 24 civilians Friday when they fired on demonstrators demanding international protection from President Bashar al-Assad's crackdown on seven months of unrest, activists and residents said.

Most of the killings took place in the central cities of Hama, where Assad sent tanks and troops to crush dissent three months ago, and Homs, a centre of increasingly armed opposition to his autocratic rule.

A no-fly zone is a legitimate demand for Homs, read banners carried by protesters in the Khalidiya neighbourhood.

NATO jets played a central role in the overthrow of Libyan leader Muammar Gaddafi, but the Western alliance has shown no appetite to intervene in Syria to halt violence which the United Nations says has killed 3,000 people.

Syria's opposition National Council has called for international protection. It has not explicitly requested military intervention, although street protesters have increasingly voiced that demand.

Assad has not used warplanes against protesters and a no-fly zone in itself would have little impact on the crackdown unless -- as in the case of Libya -- pilots attacked his ground forces and military bases.

The anti-Assad protesters have been energised by Gaddafi's death last week but their numbers are still well below those seen before a military crackdown in several cities in July.

Authorities also organised big pro-Assad demonstrations this week, with tens of thousands rallying in Damascus and the eastern town of Hasaka Wednesday, and more pouring onto streets of the Mediterranean city of Latakia Thursday.

INSURGENCY

An armed insurgency has emerged in recent weeks, mainly in rural regions and in Homs, a city of one million, 140 km (85 miles) north of Damascus, where troops and pro-Assad militiamen have assaulted old neighbourhoods that have often seen protests.

God, Syria -- We want a no-fly zone over it, shouted protesters in the Bab Tadmur neighbourhood of Homs.

In Hama, activists and one resident said Assad loyalists fired at a demonstration demanding Assad's ouster as soon at it broke out of Abdelrahman Bin Aouf mosque in al-Qusour district.

They attacked the protest immediately because the mosque is near the old Hamidiya neighbourhood and they did not want the two protests to meet, said one activist, who did not want to give his name for fear of persecution.

Since the military occupied the main square in Hama the protests have been organised in separate neighbourhoods, he said.

In the Damascus district of Barza, security forces arrested at least 40 people after they demonstrated in the capital, which has escaped most of the unrest sweeping the country.

Syria has barred most foreign media, making it difficult to verify reports from activists and from authorities, who blame foreign-backed armed groups for the violence. They say gunmen have killed 1,100 soldiers and police.

Internet footage also showed people marching against Assad in towns in Syria's Kurdish eastern region, although Kurdish anger was also directed this week against the head of the opposition National Council over comments comparing Syria's Kurds and Christians with immigrant communities in Europe.

Burhan Ghalioun told a German television station Syria was an Arab country... This does not mean denying the presence of other ethnic groups ... as we say France is France (even though) there are Muslims today and immigrants like Asians there.

Kurdish members of the council said in statement his comments resembled a chauvinism which is not much different from the extremist Baathist thinking referring to the party which has ruled Syria for nearly half a century.

Assad held an inconclusive meeting Wednesday with Arab ministers seeking to end the bloodshed by mediating a dialogue between him and his opponents and pushing for political reforms.

The Arab League had urged both sides to agree to a dialogue within two weeks -- a deadline that looms Monday.

The authorities said they had major reservations about the proposal, while opposition figures said they cannot sit down for talks unless there is a halt to the killing of protesters, disappearances and mass arrests.

Three days left, and we have 220 martyrs and counting, read a placard carried by protesters in the neighbourhood of Rankous on the edge of Damascus. Yes to dialogue -- after the downfall of the regime, said another in Homs.

(Additional reporting by Dominic Evans and Mariam Karouny in Beirut; Editing by Alistair Lyon)