Indonesia's foreign ministry on Wednesday (22 June) said there was no legal basis for former Malaysian prime minister Mahathir Mohamad's claim that the Riau Islands belonged to Malaysia.
Under international law, the nearly-1,800 islands that make up the Riau Islands province belong to Indonesia, said foreign ministry spokesman Teuku Faizasyah according to news portal Tempo.
"Indonesia does not see any legal basis and reason for Tun Mahathir's statement," he reportedly said.
"In a time when the world is facing many challenges, a senior politician should not be making baseless statements that can harm friendships."
In a speech on Sunday, Dr Mahathir had claimed that Singapore and the Riau Islands were "Malay lands" and should be "returned" to Malaysia.
"We should demand not just that Pedra Branca, or Pulau Batu Puteh, be returned to us, instead we should also demand for the return of Singapore and the Riau Islands to Malaysia as Malay lands," said the 96-year-old MP for Langkawi.
Dr Mahathir said that historically, Malay lands stretched from the Isthmus of Kra in southern Thailand to the Riau Islands.
"But today, we are left with only the peninsula... I wonder whether we will continue to own this peninsula. I am worried for the future of Malays, whether the peninsula land will also be owned by another party," he added in his speech which was uploaded online by Astro Awani.
In 2008, the International Court of Justice awarded Pedra Branca to Singapore. Malaysia applied for a review of the judgment in 2017 but withdrew the review application a year later after Dr Mahathir became prime minister for the second time.