U.N. Secretary-General Antonio Guterres appointed veteran British diplomat Martin Griffiths as the world body"s new aid chief on Wednesday, and said Griffiths would continue as the U.N. Yemen mediator "until a transition has been announced." Several sources told Reuters on Tuesday that Griffiths had been tapped to replace Mark Lowcock as the U.N. under-secretary-general and emergency relief coordinator. read more He will be the fifth British person in a row to be the U.N. aid chief. Britain last year reduced its foreign aid spending commitment to 0.5% of gross domestic product from 0.7%. Griffiths has been trying to mediate an end to the conflict in Yemen for the past three years. A Saudi Arabia-led military coalition intervened in Yemen in 2015 after the Iran-aligned Houthi group ousted the country’s government from the capital Sanaa. The Houthis say they are fighting a corrupt system. A replacement for Griffiths has to be approved by the 15-member U.N. Security Council. Griffiths told the council earlier on Wednesday that despite redoubled international efforts, the warring parties had been unable to agree a ceasefire and the Houthis had declined to meet him on several occasions. "To say this sends the wrong signal is an understatement," he said. "Stalling negotiations serves no one." He described the cooperation with the Yemen government as "excellent." Since taking office in January, U.S. President Joe Biden has made Yemen a priority and appointed special envoy Tim Lenderking to help revive U.N. efforts to end the war. U.N. aid chief Lowcock told the Security Council on Wednesday: "The humanitarian crisis in Yemen – complementing what Martin has just said on the political situation – is trapped also in a relentless downward spiral." He said 5 million people were just a step away from starving and that COVID-19 is pushing the health system to collapse.