HAVANA (REUTERS) - A fireworks explosion injured 39 people, including six children between the ages of 11 and 15, during a popular Cuban carnival on Christmas Eve, state-run media reported.

The centuries-old Parrandas festival in the central town of Remedios takes place every Dec 24 and draws thousands of Cubans and some tourists.

"An unfortunate accident with fireworks occurred last night in Remedios," the government's Cubadebate internet news service reported on Monday (Dec 25).

Among the more than 20 seriously injured, according to Cubadebate, health authorities said some were in "very grave, some less grave, and others in critical and very critical condition." All the injured appeared to be local residents, and the report did not mention that any tourists were hurt.

Remedios is located in Villa Clara province on the northern coast of the island.

Two of the town's neighbourhoods compete on Christmas Eve each year to put on the most spectacular show with floats and fireworks amidst a carnival atmosphere.

The cause of the explosion was under investigation, according to official media.