Philippine Vice-President Sara Duterte said Saturday she has contracted an assassin to kill the president, his wife and the Speaker of the House of Representatives if she herself is killed, in a brazen public threat that she warned was not a joke.

Lucas Bersamin, the country's executive secretary, referred the "active threat" against President Ferdinand Marcos Jr. to an elite presidential guards force "for immediate proper action." It was not immediately clear what actions would be taken against the vice-president.

The Presidential Security Command immediately boosted Marcos's security and said it considered the vice-president's threat, which was "made so brazenly in public," a national security issue.

The security force said it was "co-ordinating with law enforcement agencies to detect, deter and defend against any and all threats to the president and the first family."

Marcos ran with Duterte as his vice-presidential running mate in the May 2022 election, and both won with landslide victories on a campaign call of national unity.

The two leaders and their camps, however, rapidly had a bitter falling out over key differences, including in their approaches to China's aggressive actions in the disputed South China Sea. Duterte resigned from the Marcos cabinet in June as education secretary and head of an anti-insurgency body.

Like her equally outspoken father, former president Rodrigo Duterte, the vice-president became a vocal critic of Marcos, his wife, Liza Araneta-Marcos, and House Speaker Martin Romualdez, the president's ally and cousin, accusing them of corruption, incompetence and politically persecuting the Duterte family and its close supporters.

Duterte's latest tirade was set off by the decision by House members allied with Romualdez and Marcos to detain her chief of staff, Zuleika Lopez, who was accused of hampering a congressional inquiry into the possible misuse of her budget as vice-president and education secretary. Lopez was later transferred to a hospital after falling ill and wept when she heard of a plan to temporarily lock her up in a women's prison.

In a pre-dawn online news conference, an angry Sara Duterte accused Marcos of incompetence as a president and of being a liar, along with his wife and the House Speaker, in expletives-laden remarks.

When asked about concerns over her security, the 46-year-old lawyer suggested there was an unspecified plot to kill her. "Don't worry about my security because I've talked with somebody. I said 'if I'm killed, you'll kill BBM, Liza Araneta and Martin Romualdez. No joke, no joke,"' the vice-president said without elaborating and referring to the initials that many use to call the president.

"I've given my order, 'If I die, don't stop until you've killed them.' And he said, 'yes,"' the vice-president said.

Under the Philippine penal code, such public remarks may constitute a crime of threatening to inflict a wrong on a person or his family and is punishable by a jail term and fine.

Amid the political divisions, military chief Gen. Romeo Brawner Jr. issued a statement with an assurance that the 160,000-member Armed Forces of the Philippines would remain non-partisan "with utmost respect for our democratic institutions and civilian authority."

"We call for calm and resolve," Brawner said. "We reiterate our need to stand together against those who will try to break our bonds as Filipinos."

The vice-president is the daughter of Marcos's predecessor, Rodrigo Duterte, whose police-enforced anti-drugs crackdown when he was a city mayor and later as president left thousands of mostly petty drug suspects dead in killings that the International Criminal Court has been investigating as a possible crime against humanity.

The former president denied authorizing extrajudicial killings under his crackdown but has given conflicting statements. He told a public Philippine Senate inquiry last month that he had maintained a "death squad" of gangsters to kill other criminals when he was mayor of southern Davao city.