British PM presses Saudi Arabia to avert Yemen 'catastrophe'

May met both King Salman and powerful Crown Prince Mohammed bin Salman on a brief visit to Riyadh late on Wednesday, with a worsening crisis in Yemen topping her agenda.

May had promised to raise concerns over Yemen where a military coalition led by Saudi Arabia has only partially lifted a crippling aid blockade.

"The prime minister made clear that the flow of commercial supplies... must be resumed if we are to avert a humanitarian catastrophe," May's office said.

"They agreed that steps needed to be taken as a matter of urgency to address this."

Saudi Arabia is Britain's largest trading partner in the Middle East, and London has signed off on more than £3.3 billion ($4.4 billion/3.7 billion euros) worth of arms sales to Riyadh since March 2015.

That was the month that Riyadh launched its intervention against Yemeni rebels who still control the capital Sanaa and much of the north of the country.

The conflict has pushed the Arab world's poorest country to the brink of famine, killed over 10,000 civilians, displaced three million people and left much of the infrastructure in ruins.

The United Nations on Monday urged the Saudi-led coalition to do "much more" to ease the blockade impeding shipments of aid and fully reopen the key rebel-held port of Hodeidah.

UN officials have warned that Yemen faces the risk of the "world's worst famine in many decades".

May is also due to travel to Jordan on Thursday to hold talks with King Abdullah II and Prime Minister Hani Mulki. Jordan is a close British ally and a partner in the US-led coalition fighting the Islamic State group in Iraq and Syria.

Trump drew fierce condemnation at home and abroad for retweeting three incendiary anti-Muslim videos posted by the deputy head of a British far-right group who has been convicted of a hate crime.

When challenged over the tweet, he then plunged deeper into controversy by suggesting May focus on defending Britain rather than criticising him.

The strongly Islamophobic tweets were first posted by the deputy leader of Britain First, Jayda Fransen, whose anti-Muslim content was shared just days after she was charged over hate speech allegations.

A statement from Downing Street on Wednesday said Trump was "wrong" to retweet the videos.