The Philippine vice president says she will resign her Cabinet post, citing "major differences in principles and values" with President Rodrigo Duterte and an unspecified plot to remove her from the vice presidency.

Leni Robredo said Sunday that she will resign Monday as housing secretary, an appointment made by Duterte, but will stay on in her elected post as vice president.

Robredo is the second key official to resign from Duterte's administration in recent days. Maria Serene Diokno resigned as head of the government's historical commission last week to protest Duterte's decision to allow the burial of dictator Ferdinand Marcos in a heroes' cemetery.

Robredo cited her opposition to the burial as one of the issues on which she differed with Duterte.