image copyrightGetty Imagesimage captionThe explosion sent a column of fire into the sky

A huge explosion has been seen off the coast of Azerbaijan in the Caspian Sea, sending plumes of black smoke and flames into the sky.

The blast, which erupted in an area full of oil and gas fields on Sunday, was caused by a mud volcano, the government says.

None of the energy stations were damaged and no-one was hurt, it added.

Videos shared online showed a fireball and smoke rising above the sea on Sunday.

WATCH: Large explosion reported near oil platform in the Caspian Sea; officials say it may have been caused by a mud volcano pic.twitter.com/eqwNw110bF

— BNO News (@BNONews) July 4, 2021
The BBC is not responsible for the content of external sites.View original tweet on Twitter

The blast took place about 10km (6 miles) from the Umid gas field, which is 75km (45 miles) off the coast of Azerbaijan's capital Baku, state oil company Socar spokesperson Ibrahim Ahmadoc said.

The fire continued to smoulder into Monday, but was threatening neither oil and gas infrastructure nor people's lives, Azerbaijan's emergency ministry said.

It said the fire had been caused by a mud volcano.

About 400 of the world's estimated 1,000 mud volcanoes are in Azerbaijan. They spew both mud and flammable gas.

image copyrightGetty Imagesimage captionThe eruption took place in an area full of oil and gas fields

They are thought to ignite underground deposits of gas and oil to create explosions and fires.

Nicknamed the "Land of Fire", Azerbaijan is famed for its its rich oil and natural gas reserves. Explorer Marco Polo wrote about the fires in the 13th Century.

So, first, Azerbaijan is the home of mud volcanoes, and has hundreds of them.

My Google Earth mud volcano map of Azerbaijan gives you and idea of just how ludicrously many mud volcanoes there are both onshore and offshore. pic.twitter.com/m5m3yAPWSV

— Mark Tingay (@CriticalStress_) July 5, 2021
The BBC is not responsible for the content of external sites.View original tweet on Twitter

"The mud volcanoes in Azerbaijan are some of the biggest and most violent in the world. There are, on average, several large mud volcano eruptions each year, and many of them can have big fires," Dr Mark Tingay, a geophysicist at the University of Adelaide, wrote on Twitter.

The explosion follows a fire on the ocean surface in the Gulf of Mexico, which was extinguished on Friday after burning for more than five hours.

The blaze was blamed on a gas leak from an underwater pipeline.