Iran has released a South Korean tanker and 20 seafarers held since 4 January over alleged pollution offences.

The 17,400-dwt Hankuk Chemi (built 2020) was underway to Fujairah in the United Arab Emirates on Friday.

South Korea's Ministry of Foreign Affairs said in a tweet that the captain and 19 crew members were in good health.

"It's been confirmed the ship and its cargoes had no problems," it said. "The ship departed Iran after completing administrative procedures."

Tehran had said in February it would release the crew.

Pollution claim rejected

The pollution allegations against the DM Shipping-owned, Taikun Shipping-operated Hankuk Chemi were widely considered a pretence for retaliation over Seoul freezing billions in Iranian funds in South Korean banks.

Reports said the funds totalled $7bn.

The shipowner had rejected the pollution claims.

Iran was a steady supplier of oil to South Korea until former US President Donald Trump's administration cracked down on sales.

Offered to release cash

The Iranian government has denied any connection between the ship's seizure and its trapped funds in South Korea.

The South Korean foreign ministry made no mention of the money in the statement on Friday.

The government had earlier offered to release the funds, pending US approval.

The timing of the tanker's release coincides with meetings between Iranian leaders and representatives from world powers such as the US over the Joint Comprehensive Plan of Action in Vienna.

The US withdrew from the deal over Iran's nuclear weapons programme in 2018 under Trump.

New President Joe Biden has said he is willing to rejoin the agreement if Iran stops its enrichment of uranium.

Iran wants the US to lift sanctions as part of any deal.