Powerful car bombs have exploded outside two Sunni mosques in Lebanon's strife-torn Tripoli, killing 42 people and wounding hundreds.
The toll is the highest in an attack since Lebanon's 1975-1990 civil war.
Coming a week after a bombing in the Beirut bastion of Shi'ite party Hezbollah, a close ally of Bashar al-Assad, the bombings in the northern port city risk further stoking tensions between supporters and foes of the Syrian president.
"The death toll has risen to 42," a security source told AFP.
Earlier, the Lebanese Red Cross said there were also at least 500 wounded, with director Georges Kettaneh adding that many of those hurt had serious burns and head wounds.
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Both blasts hit at the hour of weekly Muslim prayers on Friday, in a community where Sunni supporters of Syria's rebels engage in frequent, often deadly, clashes with Alawites, who back the Assad regime.
The first bomb struck in the city centre at the Al-Salam mosque as worshippers were still inside.
Local television showed images from a CCTV camera of people sitting on the floor listening to a talk as cars drove past outside, when the explosion hit and the worshippers scattered in panic.
The second struck outside Al-Taqwa mosque, about two kilometres away near the port.
An AFP reporter saw a number of charred bodies near Al-Taqwa and the bodies of five children brought out.
As huge clouds of black smoke billowed into the air, television channels aired footage of the dead, of buildings with their fronts blown in and vehicles ablaze.
People rushed to help the wounded, as others hysterically sought their loved ones.
Hundreds of furious people gathered outside the mosque cursing Hezbollah and the Syrian regime.
The powerful Shi'ite movement, whose militia have been fighting for months alongside Assad's troops, linked the Tripoli attacks to the one in Beirut on August 15, which killed 22 people and injured 300.
It said they were part of a plan to "plunge Lebanon into chaos and destruction".
Former premier Saad Hariri, a Sunni and Hezbollah opponent, said the "authors of dissension do not want Lebanon to live in peace for one minute; they want the killing machine to mow down the lives of innocents across Lebanon".
Hariri's father and former billionaire prime minister, Rafiq Hariri, was assassinated in a 2005 car bombing in Beirut that also killed another 22 people which, until Friday, was the worst attack since the civil war.
In Damascus, Syrian Information Minister Omran al-Zohbi condemned this "cowardly terrorist attack on our brothers in Tripoli."
In London, Foreign Office Minister Alistair Burt condemned what he called the "abhorrent attacks" and urged unity.
"I appeal to all the people of Lebanon to pull together, to resist attempts to divide, and to renounce this attack and focus on securing a prosperous future free from the threat of violence," he said.
On Wednesday, army chief General Jean Kahwaji said his forces were fighting a "total war" against terrorism whose aim is "to provoke sectarian strife" in the country.
