North Korea has likely received more than 1 million barrels of oil from Russia over an eight-month period this year in breach of U.N. sanctions, according to an analysis of satellite imagery published on Friday by the British-based Open Source Centre and the BBC.

North Korean oil tankers have made more than 40 visits to Russia's Far Eastern port of Vostochny since March, the report on the research group Open Source Centre's website said.

"Dozens of high-resolution satellite images, AIS (Automatic Identification System) data and imagery released by maritime patrol missions tasked with monitoring North Korea’s U.N.-sanctions busting activities show North Korean tankers repeatedly loading at an oil terminal at the Russian port of Vostochny," the report said, adding that Russia's foreign ministry did not respond to a request for comment.

A U.N. spokesperson did not immediately respond to a request for comment.

North Korea has continued to illicitly import refined petroleum products in violation of U.N. Security Council resolutions, according to the UNSC.

Earlier this year, the United States and South Korea launched a new task force aimed at preventing North Korea from procuring illicit oil as a deadlock at the UNSC cast doubts over the future of international sanctions.

Under UNSC restrictions imposed over North Korea's nuclear weapons and missile development, Pyongyang is limited to importing 500,000 barrels of refined products a year.

Pyongyang and Moscow have ramped up diplomatic and economic ties in recent years, culminating in Russian President Vladimir Putin's visit to North Korea in June when the countries' leaders agreed a mutual defense pact.

The military cooperation between the two countries has been met by international alarm, with Washington, Kyiv and Seoul condemning the North for sending military equipment and more than 10,000 troops to Russia to support its war against Ukraine.

Russia's envoy to the United Nations Vassily Nebenzia said last month Russia's military interaction with North Korea did not violate international law.

North Korea has not acknowledged the deployment of troops to Russia, but said any such move would be in compliance with international law.