The Kiram family, the heirs of the late self-proclaimed sultan of the Sulu Sultanate that once ruled the Sulu archipelago, is seeking to seize the assets of Malaysia’s state energy firm Petronas through a French arbitration court ruling.

The court ruling ordered Petronas to pay $14.8 billion to the heirs and seized two of its Luxembourg-based subsidiaries.

Speaking to Daily Sabah about the landmark legal battle, a source said: "European legal and financial instruments and institutions should not be manipulated to violate the sovereignty of Malaysia from behind the fig leaf of a spurious claim to Malaysian territory by the so-called Sultan of Sulu, Sultan Jamalul Kiram II."

The Sultan of Sulu Jamalul Kiram II in 1878 willingly ceded territories and lands on the mainland of the island of Borneo to Gustavus Baron de Overbeck of Hong Kong and Alfred Dent Esquire of London as representatives of a British company. The deal was to remain "effective forever" while the sultan of Sulu was to receive compensation of about $1,000 a year.

With Malaysia gaining independence, land previously held by colonial Britain, including Sabah, became part of present-day Malaysia. Yet the Kiram family – 144 years after the original deal and backed by a European legal institution – is seeking claim to Sabah.

The claimants are Filipino citizens leading middle-class lives, a far cry from their royal ancestors of the Sulu sultanate that once spanned rainforest-covered islands in the southern Philippines and parts of Borneo island.

Malaysia argues that, since the sultanate ceded sovereignty, the arbitration was illegitimate. Kuala Lumpur further sees foreign and European backing of the Kiram family's case as an attempt to interfere in its internal affairs, reminiscent of colonial eras.

"It is part of the mess that the British left behind in Malaysia," the source said. "The Kiram family claims to Sabah are a perfect opportunity for former European empires to continue forcing their legal and financial instruments and institutions on Malaysia."

The Kirams are seeking 66.4 billion Malaysian ringgits (nearly $15 billion) as compensation for the yearly payment sealed under the deal that was stopped roughly 10 years ago.

Malaysia honored the colonial-era deal until 2013, when supporters of the late Jamalul Kiram III, who claimed to be the rightful sultan of Sulu, attempted to reclaim Sabah. Clashes erupted when about 200 supporters arrived in boats from the Philippines and lasted nearly a month.

Yet, Malaysia is arguing that the 66.4 billion ringgits is a far cry from the total amount that the yearly 5,300 ringgits would make for 10 years of compensation.

The heirs are currently seeking support from Therium, a British firm that has bankrolled legal actions by raising money from institutional investors, including a sovereign wealth fund.

The source elaborated that besides the payment sought by Therium Capital Management and the Kirams, "the Sultan’s claim has also kept open a way for European colonial intervention in Malaysia through processes that should have become redundant when the European empires around the world collapsed."

"The colonialists may have left, but they want their laws and financial practices to prevail in Malaysia. That is as unacceptable as it is offensive. Malaysia is a sovereign and independent country, it cannot be held accountable to legal norms of foreign countries, especially not those of its former colonizer."

"British legal firms, especially, use instruments via the Judicial Committee of the Privy Council – a formal body of advisers to the sovereign of the United Kingdom – to interfere in commonwealth countries, and use the U.K. Supreme Court as a kind of ‘court of last resort’ to discipline and punish former colonies," the source stressed.