Late sultan's heirs fail in bid to challenge French ruling on Malaysia dispute

France's highest civil court on Wednesday rejected an appeal by the heirs of a former sultan who sought nearly $15 billion from Malaysia's government, drawing a line under a lengthy legal battle stemming from an 1878 land deal.

Malaysia's law minister described the ruling as a "historic victory", while Paul Cohen, a lawyer for the heirs, said they were disappointed by the decision as it made "no sense".

Malaysia had been left stunned when the Filipino heirs of the last Sultan of Sulu won a $14.9 billion award in a French arbitration court in 2022, prompting them to go after Malaysian assets.

But a Paris court later upheld the Malaysian government's challenge against enforcing a partial award. The Cour de Cassation on Wednesday confirmed the decision, ruling that the award was inapplicable and void.

The 1878 deal signed between European colonists and the Sultan of Sulu for use of his territory, which spanned islands in the southern Philippines and parts of present-day Malaysia on Borneo island.

Independent Malaysia had paid a token sum annually to the sultan's heirs to honour the agreement but stopped in 2013, after supporters of the former sultanate launched a bloody incursion to try to reclaim land from Malaysia.

The heirs have maintained they had no involvement in the incursion and sought arbitration over the suspension of the payments.

In a Facebook post late on Wednesday, Malaysia's law minister Azalina Othman Said said the ruling would "definitively settle the matter in favour of the Malaysian people".

The heirs have instituted a claim against the Spanish government for alleged interference, their lawyer Cohen said in a statement to Reuters.

The Spanish arbitrator who had awarded the $14.9 billion to the heirs was convicted of contempt of court earlier this year.