A $616 million superyacht at the centre of one of the world's costliest divorce battles has been released by a Dubai court after being impounded last year, but legal wrangling over the vessel continues.

Key points: Luna was bought by Mr Akhmedov in 2014 from Roman Abramovich

Luna was bought by Mr Akhmedov in 2014 from Roman Abramovich The yacht is part of a $835 million divorce bill battle

The yacht is part of a $835 million divorce bill battle It is currently anchored in Dubai guarded by private security

Russian oil and gas billionaire Farkhad Akhmedov was ordered to pay about 40 per cent of his fortune to his former wife Tatiana Akhmedova by a London court in 2016 in one of the largest divorce settlements in legal history.

But Mr Akhmedov failed to pay the 453 million pound ($835 million) divorce bill and the court granted a worldwide freezing order, under which Mr Akhmedov's superyacht MV Luna was impounded in Dubai.

Luna, an expedition yacht built for Russian billionaire Roman Abramovich before Mr Akhmedov bought it in 2014, has at least nine decks, space for 50 crew, two helipads, a vast swimming pool and a mini submarine.

On Wednesday (local time) the Dubai court of appeal ruled that the Dubai lower courts' order to impound the yacht was wrong, allowing it to leave the port, documents seen by Reuters showed.

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But lawyers acting for Ms Akhmedova called the ruling a "procedural decision" and said the case had been referred to another Dubai court for a further hearing.

"Ms Akhmedova will simply continue to pursue her claims in the Dubai courts. She is bolstered by the fact that she successfully obtained additional orders in the English court yesterday to secure Luna," the lawyers said in a statement.

When Reuters visited the yacht on Thursday where it was moored in Dubai's Port Rashid, workers were installing new teak flooring on the large outdoor lower deck and a private security team was guarding it.

Ms Akhmedova began divorce proceedings in Britain in 2012.

Mr Akhmedov said he and his wife had already divorced in Russia in 2000, but various Russian and British courts have found no evidence to support this assertion.

Forbes estimates Mr Akhmedov's net worth is $1.9 billion.

The United States Treasury Department has put him on a list of sanctioned Russian state-owned companies and so-called "oligarchs", identified as close to President Vladimir Putin.