BEIRUT -- A rebel-claimed bombing Thursday in the northern Syrian city of Aleppo leveled a hotel near the ancient Citadel that government troops used as a military base, along with several other buildings, activists and militants said.
Syrian state television said the explosion struck a government-held area on the edge of a contested neighborhood in old part of Aleppo. The television report identified the hotel as the Carlton Citadel hotel.
The attack in Aleppo is a significant blow to President Bashar Assad's government in the north as his troops prepare to regain control of the central city of Homs following last week's cease-fire agreement after a fierce, two-year battle with the rebels trying to oust him.
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No such agreement appears to be in sight in Aleppo, Syria's largest city and former commercial hub. The city has been carved up into opposition- and government-held areas since the rebels launched an offensive there in mid-2012, capturing territory along Syria's northern border with Turkey.
In recent months, government aircraft relentlessly has bombed rebel-held areas of the city and the opposition fighters have hit back, firing mortars into government-held areas. The rebels also have detonated car bombs in residential areas, killing dozens of people.
Thursday's attack targeted a government-held area on the edge of a contested neighborhood in an old part of Aleppo. The country's official news service said terrorists -- a term the government uses for rebels -- dug up tunnels under Aleppo ancient district and detonated explosives there.
A local activist group called the Sham News Network also reported the blast, saying that Assad's troops were based in the hotel.
The Islamic Front rebel group claimed responsibility for the blast. A statement posted on its official Twitter account Thursday said that its "fighters this morning leveled the Carlton Hotel barracks in Old Aleppo and a number of buildings near it, killing 50 soldiers." It did not say how it knew how many soldiers died.
The Islamic Front is an alliance of several Islamic groups fighting to topple Assad. Many of its fighters have joined the Front after breaking away from the Western-backed Syrian Free Army last year.
Another activist group, the Britain-based Syrian Observatory for Human Rights, said Islamic Front fighters planted a huge amount of explosives in a tunnel they dug below the hotel and detonated it remotely.
It said the hotel was completely destroyed in the blast and that there were casualties among the troops.
Meanwhile Thursday, more rebels were expected to leave the central city of Homs as an evacuation of opposition fighters moves into its second day.
Homs Gov. Talal Barazi told Syrian state TV late Wednesday that that the evacuation process is being conducted in "positive atmosphere." He said Homs will be declared a "secure" city once the army moves in later Thursday.
Barazi was seen touring Homs on Lebanon's Al-Manar TV, which is owned by the Shiite militant group Hezbollah. Hezbollah has been battling rebels in Syria alongside government troops for months.
A reporter with Syrian state TV was seen broadcasting live from an entrance to Homs Old City. Standing near the city's main square known as the Clock Square, the reporter interviewed a priest who said he hoped people in the city would be safe again.
The Observatory, which has been documenting Syria's 3-year-old conflict through a network of activists on the ground, said that about 250 opposition fighters remain in the old districts of Homs, where they have been holed up under a crippling government siege for more than two years. The Observatory's head, Rami Abdurrahman, said more than 960 left the city Wednesday.
The rebels agreed to a cease-fire deal Friday as part of the evacuation.
An activist in Homs who goes with the name of Beibares Tellawi told The Associated Press that seven buses went into a once-besieged area of Homs on Thursday to take the remaining rebels out of the city.
"The siege of old Homs will be over in a few hours," Tellawi said via Skype. "We expect that everyone left inside will leave today."
In exchange for the rebels' safe departure from Homs, the opposition fighters have released 70 people who had been held by gunmen in various areas, including in Aleppo and in the coastal province of Latakia, Barazi said.
Syria's uprising began with largely peaceful protests and has evolved into a civil war with sectarian overtones, pitting largely Sunni Muslim rebels against Assad's government that is dominated by Alawites, a sect of Shiite Islam.
Islamic extremists, including foreign fighters and Syrian rebels who have taken up hard-line al-Qaeda-style ideologies, have played an increasingly prominent role among fighters, dampening the West's support for the rebellion to overthrow Assad.