Mohammed bin Salman (MBS) is wrapping up his controversial state visit to the UK, which has drawn angry protests and calls for his arrest over his role in the devastating war in Yemen.

The Saudi crown prince, who is accused of being the "chief architect" of the war, arrived on a three-day visit on Wednesday, with the ruling Conservative Party and the UK's royal family rolling out a red carpet for the young heir to the throne.

But no sooner than he landed, the 32-year-old was met by hundreds of protesters demanding an end to the violence in Yemen and an immediate halt to weapons sales from the UK to Riyadh.

In the lead-up to the trip, tens of thousands of Britons had signed online petitions calling on Theresa May, the prime minister, to cancel MBS' visit over his actions towards his southern neighbour.

Child casualties of war

According to Save the Children and UNICEF, at least 110,000 children have died from preventable causes brought about by the war in the last two years.

However, British arms companies are reported to have reaped huge benefits from the fighting, earning more than 6 billion pounds ($8.3bn) in trade with Saudi Arabia since 2015 - when the kingdom launched its massive aerial campaign against Houthi rebels.

On Thursday, a Downing Street spokesperson confirmed that new deals had been signed with Riyadh, worth more than $90bn.

It was not immediately clear whether any of those contracts included arms sales, with the spokesman simply adding that the signed deals included "direct Saudi investment in the UK and new Saudi public procurement with UK companies".

James Denselow, the head of humanitarian policy and advocacy for Save the Children, told Al Jazeera that despite glowing appraisals from Boris Johnson, the UK foreign secretary, Saudi Arabia had precipitated "a humanitarian disaster.

"There are 11 million children in Yemen dependant on humanitarian aid, that's a number greater than the entire population of Belgium," he said.

"So for all the trade deals, and all the niceties, we have to remember Saudi Arabia is a key player in this conflict."

On Wednesday, the leader of the opposition, Jeremy Corbyn, criticised May and her government's lack of criticism of Saudi Arabia, arguing it was "colluding" in war crimes by selling arms to Riyadh.

May, however, defended her government's relationship with the kingdom, arguing that the UK played an influential role in bringing to light the many issues Saudi Arabia faces.

The crown prince, who is heir to his 82-year-old father, King Salman, said there were "huge opportunities" to boost trade between the two countries and they had to work together to deal with "failed states ... terrorist and extremist organisations" in the Middle East.

