Authorities said a "technical accident" occurred at the Barzan local gas supply facility on Sunday evening .
Qatar, which hosts a major US military base, has come under repeated Iranian missile and drone attacks during the Iran war, which trapped about 20 per cent of global LNG supply in the Gulf before some shipments began to resume recently.
Qatar's energy ministry said in a statement that 13 people had died and 66 were injured.
It said the plant's export capabilities were unaffected and there was no risk to the environment.
QatarEnergy did not provide detail on where in the plant the explosion took place nor the extent of the damage but Saad al-Kaabi, CEO of QatarEnergy CEO and Qatar's energy minister, said an investigation had started into the incident.
The blast rattled windows and was felt across central Doha, panicking residents more than 70km from Ras Laffan.
The incident highlights the challenges Gulf producers face in ramping up oil and gas production from facilities shut in during the Iran war.
Qatar has been among the hardest hit by the closure of the Strait of Hormuz as it has no alternative routes to export its LNG.
Restarting LNG operations is a particularly complex process due to a deliberately slow cooldown to avoid thermal shock.
LNG trains cannot restart simultaneously and must be brought back in sequence.
In the liquefaction process - which turns gas into a liquid state by cooling it down to approximately minus 162C - the cooldown is the most critical step.
The facility is located in Ras Laffan Industrial City, QatarEnergy's site for LNG production and export with an annual production capacity of 77 million metric tons.
An Iranian missile attack in March struck two of its key gas-processing units, slashing about 17 per cent of Qatar's LNG export capacity which QatarEnergy's CEO told Reuters would take three to five years to repair.
The war also forced the company to remove about 10,000 workers from offshore rigs and onshore processing plants.
The company reported no injuries during the March missile attack.
