The Russian parliament has rubberstamped a bill that could lead to a major revision of licences for shallow-water acreage in the Black and Azov seas that Russia claims it now owns.

According to the bill, licences issued by Ukraine for acreage in both seas will be considered null and void after the document is published and becomes officially enacted.

The bill is expected to hit Chernomorneftegaz, a major gas producer operating several offshore blocks around the Crimea Peninsula, which Russia annexed from Ukraine in 2014.