Russia's oil export revenue sank 42 percent in February as Western powers tightened sanctions on the country in the wake of the Ukraine war, the International Energy Agency said on Wednesday.

The country earned $11.6 billion from its oil exports last month after the European Union imposed a ban on Russian petroleum products alongside a price cap agreed with the Group of Seven and Australia, according to the IEA.

This was down from $14.3 billion in January and a 42 percent drop from $20 billion in February last year.

Russia, however, was still shipping "roughly the same" amount of oil to world markets, according to the IEA, which advises wealthy nations.

"This indicates that the G7 sanctions regime has been effective in not restricting global crude and product supplies, while simultaneously curtailing Russia's ability to generate export revenue," the IEA said.

Russian oil exports fell by 500,000 barrels per day to 7.5 million bpd in February, with a big drop in shipments to the EU.

"Recent tanker tracking data suggest that Moscow has managed to re-route most of the barrels previously destined for the EU and US to new outlets in Asia, Africa and the Middle East," the IEA said.

"Although it has been relatively successful in sustaining volumes, Russia's oil revenue has taken a hit."