Two tankers involved in an alleged illegal ship-to-ship oil transfer were spotted while on patrol for an embargo enforcement mission against North Korea, the French Navy has said.

On Feb. 28, the French frigate Prairial was deployed to the East China Sea to contribute to the UN embargo against the North and identified the two oilers during a suspected nighttime transfer, the France Pacific Command (ALPACI) wrote on Twitter Tuesday.

ALPACI released four photos of the suspected tankers involved in what appears to be an illegal ship-to-ship transfer.

It did not provide further details, including whether or not the tankers in question belong to the North.

In response to the North's launch of an intercontinental ballistic missile in 2017, the United Nations placed international sanctions on Pyongyang, prohibiting all member countries from engaging in ship-to-ship transfers of goods to or from North Korean-flagged vessels. (Yonhap)