France on Wednesday condemned Iran's seizure of a South Korean tanker in strategic Gulf waters and called for the vessel's immediate release.

"This incident is fuelling tensions in the region," the French foreign ministry said in a statement.

"France calls for the immediate release of the ship and its crew," it added, stressing the need to preserve the freedom of navigation.

On Monday, Iran's Revolutionary Guards seized the South Korean-flagged Hankuk Chemi and arrested its multinational crew of 20 near the Strait of Hormuz, a chokepoint through which a fifth of world oil output passes, alleging the tanker had polluted the area's waters.

The Guards said the arrested crew were from South Korea, Indonesia, Vietnam and Myanmar.

South Korea has demanded the ship's release and deployed a destroyer to the area -- though with no plans to engage in an offensive operation, an unnamed military official told Yonhap News Agency.

Seoul has said it will send a government delegation to Iran to negotiate the release of the vessel and its crew.

Iran's move came after Tehran had urged Seoul to release billions of dollars of Iranian assets frozen in South Korea as part of the US sanctions.

The incident was the first seizure of a major vessel by the Iranian navy in more than a year.

In July 2019, the Guards seized the British-flagged oil tanker Stena Impero in the sensitive Strait of Hormuz for allegedly ramming a fishing boat and released it two months later.

It was at the time widely seen as a tit-for-tat move after authorities in the British overseas territory of Gibraltar detained an Iranian tanker and later released it over US objections.

Tehran denied the two cases were related.

The Guards seized at least six other ships in 2019 over alleged fuel smuggling.

dla/pvh/spm