The U.N. Security Council has condemned the double car bomb blasts in Lebanon Friday that killed at least 42 people and left more than 500 wounded.
The 15-member council appealed to all Lebanese people to preserve national unity in the face of attempts to undermine Lebanon's stability.
Separately, U.N. Secretary-General Ban Ki-moon urged Lebanese citizens to "exercise restraint, remain united and to support their state institutions," particularly Lebanon's security forces.
Friday's attacks took place in the northern city of Tripoli.
One of the bombs exploded outside the Taqwa mosque as midday prayers were ending. That mosque is where Sheik Salem Rafei, a Salafi cleric opposed to Lebanon's militant Shi'ite Hezbollah group, usually prays. It was not clear whether he was inside.
The second bomb went off about five minutes later outside the Al Salam mosque in Tripoli's Al Mina district.
Hassan Kamel, who was there, said, "The sheikh was in the mosque praying and suddenly the explosion happened."
Kamel said "destruction and bodies and wounded" were everywhere. "We condemn everything that is happening here in Tripoli," he added.
Murky battle lines
There was no immediate claim of responsibility. The Shi'ite militia group Hezbollah condemned the attacks, saying they appeared to be an effort to incite more sectarian violence in Lebanon.
Tensions have been rising in Lebanon during the civil war in neighboring Syria, especially in Tripoli, where Sunni Muslims who support the armed uprising in Syria have clashed repeatedly with Alawites who support President Bashar al-Assad.
An anti-Hezbollah Islamist group calling itself the Brigades of Aisha said it carried out a car bombing last week in Rweiss, a southern suburb of Beirut that is a Hezbollah stronghold. That blast killed 22 people and wounded more than 200.
Smoke rises outside al-Taqwa mosque, one of two mosques hit by explosions, Tripoli, Lebanon, August 23, 2013.
People carry a body outside one of two mosques hit by explosions in Lebanon's northern city of Tripoli, August 23, 2013.
Civilians are seen near a burning car outside one of two mosques hit by explosions, Tripoli, Lebanon, August 23, 2013.
Sunni Sheikh runs as he holds a burned body outside one of two mosques hit by explosions, Tripoli, Lebanon, August 23, 2013.