Britain could withdraw from UNESCO, following Israel, Trump administration
Following on from the Trump adminstration and Israel, Mordaunt has requested to pull £11.1million of funding by the end of next year.
However the move has alarmed Prime Minister Theresa May, Michael Gove and foreign office colleagues, The Times reported.
The idea was first touted by Mordaunt's predecessor in 2016 Priti Patel and then vetoed by May, who has reportedly not changed her view on the UK's membership.
Britain played a vital role in the formation of UNESCO which is best-known for its prestigious World Heritage List, and also runs science, educational and cultural programmes.
The US withdrew from the organisation in October 2017 after accusing the global body of "anti-Israel bias". Israel followed suit a few hours later, with Prime Minister Binyamin Netanyahu saying the US decision was "brave and moral".
The United States was angered in 2011 when UNESCO members granted Palestine full membership, and withdrew funding from the organisation.
The Department for International Development (DfID) ranks the cultural agency as its worst performing partner, and Mordaunt believes it does not meet the department's spending criteria.
Her proposal has stoked fears Britain would become further isolated from the international community following Brexit.
The suggestion has also angered Labour frontbencher Emily Thornberry who said the move was intended to "curry favour" with Trump and Netanyahu.
She pointed out that when the Thatcher government withdrew from the body in 1985, former prime minister Edward Heath said it reflected a "narrow-minded nationalism which believes that we can survive without the rest of the world". Britain rejoined 11 years later.
"If Penny Mordaunt was truly worried about the organisation’s financial difficulties, she would stay inside it and help reform an organisation that Britain helped create," Thornberry added. "To just walk away instead is an act of political petty-mindedness and shameless cultural vandalism."
The DfID is consulting with other departments on the move before any final decision is made.
Meanwhile, senior cabinet minister Mordaunt is among MPs believed to be resigning imminently over the prime minister's Brexit deal.