"Our fighters have nothing to do with this explosion," Fırat News, a website close to the terrorist organization, cited the PKK as saying in a statement.
There was no immediate claim of responsibility for the explosion, which officials said was caused by a remote-controlled car bomb, but southeastern Turkey has seen frequent attacks by the PKK, designated a terrorist group by Turkey, the United States and European Union.
Turkey has accused neighboring Syria of supporting the PKK, which launched a separatist insurgency in the region 28 years ago, since when more than 40,000 people have been killed.
Gaziantep is around 50 kilometers (30 miles) from the Syrian border. Turkey has opened a centre in the town to receive international aid as it copes with an influx of almost 70,000 Syrian refugees fleeing fighting across the border.
The Kurdistan Freedom Hawks (TAK), a group connected to the PKK, has claimed responsibility for some past attacks in Turkey outside the PKK's regular area of operation.
PKK denied responsibility for attacks in the past
İsmail Avcı, Diyarbakır
The denial by the terrorist Kurdistan Workers' Party (PKK) of having had a hand in the Gaziantep attack has brought to mind a question over whether it may be refraining from claiming responsibility out of fear of a strong reaction from Gaziantep locals.
The PKK has denied responsibility for several bloody attacks in the past just to claim responsibility for them several weeks later.
In 2011, for example, four young women were killed in the southeastern province of Siirt when assailants attacked their van with rifles and hand grenades. Fearing the reaction of locals, the PKK said it was not behind the attack. However, a few weeks after the attack it did claim responsibility.
In 2009, nine Turkish soldiers were killed when a military vehicle drove over a land mine planted by the terrorist PKK in Diyarbakır's Lice district. The PKK denied responsibility but later said the attack had been carried out by “local branches in protest of military operations against the PKK.”
In January 2008, six students were killed in an attack targeting a military vehicle transporting a number of military personnel in Diyarbakır. A total of 52 people were wounded and seven killed, including six students who were studying at a university examination preparation center nearby. The PKK initially said it was not behind the attack but later announced that its “local branches” had carried out the attack without its approval.
A bomb blast in Diyarbakır in September 2006 killed 10 civilians, including seven children. The bomb was planted in a thermos and left along the side of a road in the district of Bağlar. In the aftermath of the deadly bombing, the PKK denied responsibility; however, a group affiliated with the PKK claimed responsibility for the attack.