Saudi Crown Prince Mohammed bin Salman's visit to London will turn to defense and security on Friday as he meets British defense minister Gavin Williamson, touching on the most contentious element of his trip: arms sales.
Downing Street said a target of £65bn worth of trade and investment had been agreed during the Prince's United Kingdom visit.
A Saudi-led coalition has been battling Iran-allied rebels in Yemen since 2015 in a war that has killed more than 10,000 people and driven the Arab world's poorest country to the brink of starvation.
Prince Mohammed and the British Minister of Defense signed two memorandums and coordinated arrangements to strengthen defense capabilities and deepen cooperation and partnership through the transfer of technology, industrial partnership, training, research and development and technical consultation in accordance with Vision 2030.
But such close ties have displeased some, particularly regarding Saudi Arabia's military intervention in Yemen.
The UK government has faced criticism from opposition leaders and campaigners about selling military hardware to Saudi Arabia during the ongoing humanitarian crisis in Yemen.
Save the Children's chief executive Kevin Watkins warned Saudi Arabia is targeting children in the brutal war in Yemen with a "growing sense of impunity".
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The complaint says the law violates the second amendment of the United States constitution, which governs the right to bear arms. In schools, the measure also creates new mental health programs and establishes an anonymous tip line for reporting threats.
Speaking in London at the launch of The War On Children, a report into crimes against children in warzones, Mr Watkins said: "It has become acceptable to operate humanitarian blockades which, if not explicitly created to starve children and harm children, will have that inevitable effect".
Crown Prince of Saudi Arabia Mohammed bin Salman leaves 10 Downing Street in London, March 7, 2018.
"The fact that you can rape, murder, kidnap, bomb schools, bomb clinics with no effect, speaks I think to the heart of the deeper challenge that we are addressing today".
The deal for the Typhoon fighters has become bogged down in negotiations over where production of the jet will take place, with Saudi Arabia keen to have some parts of the process on Saudi soil.
Before his visit, the 32-year-old royal said both countries would be "much safer if you have a strong relationship with Saudi Arabia".
"We're all concerned about the appalling humanitarian situation in Yemen", May said, adding she meant to raise "concerns about human rights when I meet him".