MANILA (AFP) -- Philippine Vice-President Leni Robredo said Sunday she would quit President Rodrigo Duterte's cabinet after being told to stay away from its meetings, and alleged there was a plot to oust her as his deputy.

Robredo did not say who was behind the alleged plot to remove her as vice-president.

But she cited "major differences in principles and values" with Duterte, such as over the rash of extrajudicial killings during his "war on drugs" and the hero's burial he granted to dictator Ferdinand Marcos.

In the Philippines the president and vice-president are elected separately. Duterte and Robredo come from rival parties.

"I had been warned of a plot to steal the Vice-Presidency. I have chosen to ignore this and focus on the job at hand. But the events of recent days indicate that this plot is now being set in motion," Robredo said in a statement on her Facebook page.

"I will not allow the Vice-Presidency to be stolen" despite leaving the cabinet, she said.

"We received a text message last Saturday from Cabinet Secretary (Leoncio) Evasco, relaying the   President's instruction... for me 'to desist from attending all Cabinet meetings starting this Monday, December 5'."

"This is the last straw, because it makes it impossible for me to perform my duties," Robredo said.

She had been named to the cabinet as a housing official. Philippine presidents have traditionally named vice-presidents to their cabinets, even when they come from rival parties.

Duterte's war on drugs has claimed thousands of lives and sparked international criticism.

His spokesman Martin Andanar, interviewed on ABS-CBN television on Sunday, confirmed Robredo's departure from the cabinet and cited "irreconcilable differences".

Regarding the alleged plot to unseat her from the vice-presidency, Andanar said: "If there is a plot, that plot did not come from the camp of the president."

"Tomorrow, let us see if the president actually accepts her resignation (from the cabinet)," he added.

Evasco confirmed separately that he had sent Robredo a message, telling her not to attend further cabinet meetings on the instructions of Duterte.

He said there was no order to strip Robredo of her housing position.

Duterte won presidential elections in May after pledging to kill tens of thousands of drug suspects, warning that otherwise the Philippines would turn into a narco-state.

Since he assumed office, some 4,800 people have been killed by police or unidentified attackers.