MANILA - Malaysian Foreign Affairs Minister Hishammuddin Hussein on Wednesday called out Philippine Foreign Affairs Sec. Teodoro Locsin Jr. for saying "Sabah is not in Malaysia".

Commenting on Locsin's tweet, Hishammuddin reiterated that Sabah is a territory of Malaysia.

He also said the Ministry of Foreign Affairs will ask the Philippine ambassador for an explanation.

"This is an irresponsible statement that affects bilateral ties. @MalaysiaMFA will summon the Philippines Ambassador on Monday to explain. Sabah is, and will always be, part of Malaysia," he wrote.

The current Philippine Ambassador to Malaysia is former Department of Foreign Affairs spokesperson Charles Jose.

Locsin earlier berated the US Embassy in the Philippines on Twitter for saying that Sabah is in Malaysia, referring to the Philippines' claim to the territory.

• Sabah not in Malaysia? Locsin blasts US Embassy's 'Sabah, Malaysia' photo caption

The US Embassy has not responded to a request for comment nor has it edited its tweet.

The Philippines laid claim over Sabah, a territory part of Malaysia’s northern Borneo, citing a land lease agreement in 1878 between the Sultanate of Sulu and the British North Borneo Chartered Co.

There had only been intermittent discussions between the Philippines and Malaysia over the claim, and the latter has continued to govern the territory. In November 2016, Duterte and then Prime Minister Najib Razak agreed to set aside the dispute.

In 2013, hundreds of militants from Tawi-Tawi went to Lahad Datu in Sabah to assert their claim, calling themselves "Royal Security Forces of the Sultanate of Sulu and North Borneo.”

Malaysia has sentenced 9 Filipinos to death over the incident.

In 1968, Republic Act 5446 or the law on Philippine baselines included "the territory of Sabah, situated in North Borneo, over which the Republic of the Philippines has acquired dominion and sovereignty."

It was amended in 2009, but a Supreme Court decision said Republic 9522 or Baselines Law still did not relinquish the Philippine claim to Sabah, a claim Malaysia has rejected.

• The claim to Sabah: A historical perspective

- with a report from Willard Cheng, ABS-CBN News