Liew, who then held the ministerial portfolio for law, said the claim had cost pain and lives on both sides of the border.
“It also seriously impacted economic confidence and investment in the sub-region.
“Sabahans clearly made their choice in the Cobbold Commission. The Malaysia Agreement of 1963 has been accepted as a treaty by the United Nations.”
The Philippines, he pointed out, has an embassy in Malaysia and not just in Malaya.
“Sabah has been part of Malaysia for 57 years and does not need any more of this talk of being claimed,” said Liew.
“Thus, politicians need to be more responsible with their statements. They should not inflame nationalistic sentiments just to score short-term political brownie points.
“In order for long-term solutions that ensure the health, happiness and well-being of our people for generations to come, we require rational statesmanship and sustained investment in development.
“Such efforts would be more beneficial for the people than mere jingoism.”
Liew said that the Philippine government would do well to focus on solving the poverty, inequality and underdevelopment issues in the Southern Philippines instead of interfering in Sabah and Malaysian affairs via this claim.
“The claim had been extinguished by the abolition of the Sultanate of Sulu when the Philippines became a republic back in the 1930s.”
Liew said there were serious religious and developmental issues in Southern Philippines that were in dire need of fair and just treatment by Manila.
“Sustained development investment in a stable economic climate along with peace-building efforts and confidence-raising measures would go far to make Asean a success, by making it a zone of peace, freedom and neutrality with a regional organisation that seeks to prosper each neighbour.
“This is what is desperately needed in South East Asia and in the Sulu Sea region at this time.”
Liew said claims that inflame irrational nationalism would not help.
“We need to respect and prosper each other together in Asean. Politicians need to lead by example.
“As an integral and indissoluble part of Malaysia, Sabah stands ready to support the federal government’s efforts to ensure that we achieve this goal of prospering all in Sabah and in Asean via multi-lateral mechanisms.”
Foreign Affairs Minister Datuk Seri Hishammuddin Hussein yesterday said Locsin’s tweet that Sabah is not in Malaysia was “irresponsible” and would affect bilateral ties.
He stressed that “Sabah is, and will always be, part of Malaysia”.
“No country can tell another what it can and cannot say about what the latter regards as rightfully its own,” Locsin said on his Twitter account in reply.