A powerful blast at around Friday midnight hit an about 240-km long natural gas pipeline connecting Azerbaijan and Russia.
The pipeline runs along the Caspian Sea coast to Russia's North Ossetia.
According to Azerbaijan's APA news agency, the incident took place at the Shamakhy region in central Azerbaijan, at the 13th mile of the Gazimagomed-Mozdok pipeline.
The explosion was followed by a blaze, with flames raging at the height of up to 150 metres. There were no death or injuries.
It was, however, extinguished shortly after midnight Saturday, the Baku-based Trend news agency said.
According to police, gas supplies to Russia have been suspended and its resumption is unclear.
Though APA said the blast was caused by a gas leak, Trend said the cause of the explosion is yet to be established.