The explosion is the latest attack to have rocked the key NATO member in a horrific year that has seen a string of strikes blamed on Kurdish and Islamist militants as well as a bloody July 15 botched coup.
Governor Ali Yerlikaya of Gaziantep, where the attack happened said in a statement that 30 people had been killed and 94 wounded in "an abhorrent terror bomb attack on a wedding".
A previous toll had put the number of dead at 22.
"We condemn the traitors who organized and carried out this attack," he said, vowing that those responsible would be "brought to account".
Mehmet Erdogan, a ruling Justice and Development Party (AKP) lawmaker for Gaziantep said it was not clear who was responsible for the explosion but there was a "high possibility" it was a suicide attack.
The lawmaker added that it was the type of attack that could have been launched by the Islamic State (IS) group or the Kurdistan Workers' Party (PKK).
"IS the culprit"
The explosion took place in the Sahinbey district of the city which is said to have a large number of Kurdish residents, fuelling speculation of Islamic State (IS) jihadist involvement. Reports said the wedding had a strong Kurdish presence.
"Initial information suggests it is Daesh (IS) who did this," Gaziantep MP for the AKP, Samil Tayyar, was reported as saying by Dogan news agency.
He added: "It is an area where many of our Kurdish brothers live."
The pro-Kurdish Peoples' Democratic Party (HDP) said its members had been present at the wedding which was also attended by many women and children.
"The aim of terror is to scare the people but we will not allow this," said Deputy Prime Minister Mehmet Simsek, who also represents Gaziantep in the Turkish parliament, adding that a suicide bombing was the likely cause.
A major city lying just 60 kilometers (37 miles) north of the Syrian border, Gaziantep has become a hub for Syrians fleeing the civil war in their country.
But as well as refugees and opposition activists, there have long been fears it was home to a significant jihadist presence.
Images from the scene showed bodies covered in white sheets while distraught relatives of the victims were comforted in the street.
Turkey has already been hit by a bloody year of militant attacks in its two biggest cities that have left dozens dead.
Kurdish militants have twice struck in Ankara in deadly attacks, while IS suicide bombers have twice killed tourists in the center of Istanbul.
Meanwhile the country is still reeling from a failed July 15 coup blamed on the U.S.-based Islamic preacher Fethullah Gulen that has been followed by a relentless purge of his supporters from all state institutions.
Twelve people were killed on Thursday in a spate of bombings against Turkish security forces blamed on the Kurdistan Workers Party (PKK) who appear to have ramped up their campaign of attacks in the aftermath of the failed coup.
As has been the case in previous attacks, Turkey's broadcasting regulator RTUK banned broadcast of footage from the scene of the attack in Gaziantep.
Information and Communication Agency (BTK) head Omer Fatih Sayan told state-run Anadolu news agency that those sharing images of the bombing would face prosecution.
"More active Turkey"
The blast in Gaziantep came on the day Turkish Prime Minister Binali Yildirim vowed Ankara would play a "more active" role in the next six months in efforts to solve the over five-year Syrian civil war.
In a sign that Turkey's position was becoming gradually more aligned with Russia and Iran, he added that Syrian President Bashar al-Assad could remain temporarily during a transition period.
Iran and Russia are the main allies of Assad whereas Turkey has always insisted his exit was a precondition for the end of the conflict.
Turkey was long accused of turning a blind eye to or even abetting the rise of IS in Syria, claims it vehemently denies.
However Western states say Ankara has begun to move strongly against the group and seal its borders to jihadist traffic after the attacks blamed on IS on its soil this year.
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