By Khaled Yacoub Oweis

AMMAN (Reuters) - The killing of Libya's Muammar Gaddafi fueled anti-government rallies across Syria after Friday prayers and security forces killed 13 people in a continued crackdown on protesters seeking President Bashar al-Assad's ouster, activists said.

Protesters found a heavier than normal security presence in Syria on the day after Gaddafi's death, which could embolden protesters across an Arab world where unrest has toppled three autocratic leaders this year and challenged others like Assad.

Most of Friday's killings were in the central city of Homs and in Hama to the north, both hotbeds of anti-Assad protests and the targets of major military operations to put them down.

Homs, the city of one million, has also witnessed a nascent insurgency emerging after repeated attempts by tank-backed troops to suppress demonstrations calling for an end to 41 years of Assad family rule and more political freedoms.

"Gaddafi is finished. It's your turn now Bashar!" shouted demonstrators in the town of Maaret al-Numaan in the northwestern province of Idlib, according to one witness.

"Prepare yourself Assad!" chanted protesters in the town of Tayyana in the tribal province of Deir al-Zor, on the border with Iraq.

Gaddafi died in unclear but bloody circumstances shortly after the fugitive former strongman was captured by transitional government forces, two months after he was driven from power.

Assad, an ophthalmologist who inherited power from his late father in 2000, strengthened ties with Gaddafi months before the tide of popular Arab unrest against repressive ruling elites erupted in Tunisia in December.

The two countries struck a series of cooperation deals and Assad later allowed a Syrian-based satellite station to broadcast messages from Gaddafi while he was on the run. He was killed in unclear circumstances after his capture on Thursday.

The opposition movements Syria and Libya were drawn closer by what an activist called "enduring the same tyranny."

Libya's new rulers were quick and alone so far to recognize Syria's opposition National Council, formed this month in Istanbul, as the legitimate authority in Syria.

"(Gaddafi's) death has positively reflected on the protesters in Syria. It has given them more confidence that their struggle will eventually lead to the results they are expecting," said Omar Idlibi of the grassroots Local Coordination Committee in Beirut, who is also a member of the National council.

"SUFFERING OF SYRIANS AND LIBYANS THE SAME"

"The suffering of the Syrian and Libyan people is the same. The two regimes are the same and they were helping each other."

SECURITY STEPPED UP

Activists and residents said Syrian authorities have stepped up security in several cities and towns including the Damascus suburbs and Talbiseh near Homs.

"(There is an)unprecedented presence of security today with snipers on rooftops and roadblocks inside the suburb," an activist in Damascus suburb of Saqba said.

Demonstrations also broke out in the ethnically Kurdish regions of Qamishli, Derbaseyeh, Malikiya and Amouda.

In the town of Houla northwest of Homs, a crowd of several thousands held shoulders and waved old Syrian flags dating to before Assad's Baath party took power in a coup 48 years ago.

"Doctor (Assad), you are next!" read banners carried by the villagers, according to live video footage.

Demonstrations also flared in Homs, the provincial capital 140 km (85 miles) north of Damascus, where three members of one family were also shot dead at an army roadblock in Bab Sbaa district on their way to prayers, local activists said.

Syrian authorities say they are fighting "armed terrorist groups" in Homs who have been killing civilians, prominent figures and troops. The authorities have banned most foreign media, making verification of events on the ground difficult.

Authorities say at least 1,100 police and soldiers have been killed. The United Nations says Assad's crackdown has killed 3,000 people, including 187 children.

Assad has responded to the protest groundswell with promises of reforms which the opposition describes as hollow because he has also sent troops and tanks into cities and towns to crush the unrest.

But protests have persisted, although in reduced numbers, with several thousand soldiers from the mainly Sunni Muslim ranks now challenging his rule.

Several officers have recently announced their defection, although most deserters have been Sunni conscripts who usually man roadblocks and form the outer layer of military and secret police rings around restless cities and towns.

The officer corps of Syria's army is composed mainly of members of Assad's minority Alawite community.

(Writing by Mariam Karouny; Editing by Mark Heinrich)