Arab League peace monitors arrived in the Syrian city of Homs on Tuesday for a first look after tanks were seen leaving the hotbed of anti-government unrest where hundreds have been killed during nine months of military crackdowns on protesters.

The team of monitors were expected to see for themselves whether President Bashar al-Assad is keeping a promise to cease military action in Syria's cities to crush demonstrations that began in March. At least 5,000 people have been killed in the spreading bloodshed by a U.N. count.

The observers began their visit by meeting the governor of Homs, Syria's Dunia television channel said. According to opposition activists at least 34 people were killed in the city on Monday as tanks fired at targets among apartment blocks.

The British-based Syrian Observatory for Human Rights cited reports from opposition activists in Homs saying at least 11 tanks had left a district they attacked on Monday, and that other tanks were being hidden.

Opponents of Assad say districts of Syria's third biggest city have been hammered by government troops and tanks in recent days, with the Baba Amr neighbourhood taking a pounding from tank fire, mortars and heavy machineguns.

My house is on the eastern entrance of Baba Amr. I saw at least six tanks leave the neighbourhood at around 8 in the morning (0600 GMT), Homs activist Mohamed Saleh told Reuters by telephone. I do not know if more remain in the area.

Amateur video recorded by activists on Monday showed tanks prowling around Baba Amr, firing at unseen targets. Video showed gruesome pictures of mangled bodies in the wreckage of building that bore the signs of shelling.

It's been completely quiet the whole morning, so we're going to use the time and hold a protest, said construction worker Tamir, from the Khalidiya district in Homs, one of the four areas where fighting has been heavy in past weeks.

I haven't heard or seen anything that suggests tanks are leaving, I don't believe it. Earlier today I was on my roof where we can see six of the tanks in the area, three are in one roundabout, three are in another. They are still there, he said, speaking by telephone as the monitors arrived.

Assad's opponents fear that the monitors - who arrived in the country on Monday after weeks of negotiations with Arab states - will be used as a cloak of respectability for a government that will hide the extent of violence.

The say tanks have been withdrawn before from restive cities such as Deraa and Hama, only to return later.

The monitoring mission launch marks the first international intervention on the ground in Syria since the start of the popular revolt inspired by Arab pro-democracy uprisings that have toppled several dictators this year.

The Arab mission, led by Sudanese General Mustafa Dabi, is starting with 50 monitors who arrived in Damascus on Monday and will be split into five teams of ten. About 100 more monitors are to follow soon.

The teams will use government transport, according to Dabi. But that arrangement likely to fuel charges by the anti-Assad opposition that the monitoring mission will be impeded and hoodwinked from the outset.

Arab League delegates insist the mission will nevertheless maintain the element of surprise and be able to go wherever it chooses with no notice.

The monitors are meant to determine whether the government is abiding by a peace plan that requires it to withdraw troops from cities, free prisoners and open dialogue with its opponents. Assad has so far shown no sign implementing the deal.

At least 34 people were killed in Homs on Monday as tanks fired into districts where opposition has been strongest to Assad's rule, the Observatory said. Their names were recorded.

Amateur video posted by activists on the Internet showed tanks in action in Baba Amr, with bodies lying in pools of blood on a narrow street. Power lines had collapsed and cars were burnt and blasted, as if shelled by tank or mortar rounds.

What's happening is a slaughter, said Fadi, a resident living nearby.

Destruction inflicted by heavy weapons was evident. The video images were impossible to verify -- because Syria has barred most foreign media from the country -- but hard to fake.

Assad says he is fighting Islamist terrorism directed from abroad and that some 2,000 people have been killed, mainly soldiers and police.

AVERTING CIVIL WAR

An armed insurgency is eclipsing civilian protest in Syria. Many fear a slide to sectarian war between the Sunni Muslim majority, the driving force of the protest movement, and minorities that have mostly stayed loyal to the government, particularly the Alawite sect to which Assad belongs.

Analysts say the Arab League is anxious to avoid civil war. Western powers have shown no desire to intervene militarily in a volatile neighbourhood of Middle East conflict, and the United Nations Security Council is split.

Assad's opponents appear divided on aims and tactics. He retains strong support in important areas -- including Damascus and the second city Aleppo -- of the country, and maintains an anti-Israel alliance with Iran.

Fighting in Homs has intensified since a double suicide bombing in Damascus on Friday that killed 44 people.

At least ten army defectors were killed in fighting with security forces in the suburb of Douma outside Damascus, according to the British-based Syrian Observatory for Human Rights. The group estimated the death toll may be higher, in the dozens, with casualties at a similar rate among security forces.

Homs resident Fadi told Reuters via Skype that residents and rebel fighters were trapped by trenches the army had dug around the Baba Amr neighbourhood in recent weeks.

They are benefiting from trenches. Neither the people nor the gunmen or army defectors are able to flee. The army has been descending on the area for the past two days.

Others said the army was also taking a hit.

The violence is definitely two-sided, said a Homs resident who gave his name only as Mohammed to protect his safety. I've been seeing ambulances filled with wounded soldiers passing by my window in the past days. They're getting shot somehow.

Parts of Homs are defended by the Free Syrian Army, made up of defectors from the regular armed forces, who say they have tried to protect civilians.

(Writing by Douglas Hamilton; Editing by Mark Heinrich)