Saudi Arabia's Crown Prince Mohammed Bin Salman will hold talks with Defence Secretary Gavin Williamson on the final day of his official visit to the UK.
The Gulf state is an important defence partner for the UK, but the sale of arms to the country is highly controversial, especially since its intervention in Yemen.
Ahead of his visit, the crown prince signalled the importance of the UK-Saudi Arabia relationship to security.
He said the people of both countries would be "much safer if you have a strong relationship with Saudi Arabia".
The meeting with the Defence Secretary comes after Mr Bin Salman was treated to a private dinner with the Prime Minister at Chequers on Thursday night.
The pair dined on halibut with cucumber, radish and lemon, followed by Chiltern lamb rack with lamb shoulder broth and new potatoes, and a dessert of Yorkshire rhubarb cheesecake with ginger.
The Campaign Against Arms Trade said the UK has licensed £4.6 billion of defence exports to Saudi Arabia since 2015, when it began its action in Yemen.
They included £2.7 billion worth of licences relating to aircraft, helicopters and drones and £1.9 billion relating to munitions and countermeasures.
Labour leader Jeremy Corbyn has accused the Government of "colluding" in war crimes by Saudi forces engaged in Yemen's bitter civil war.
The Labour leader said British military personnel were "directing" Saudi military operations responsible for large-scale civilian casualties.
Downing Street said Mrs May brought up the issues of Yemen and human rights in talks with the crown prince on Wednesday.
A spokeswoman said the Prime Minister raised "our deep concerns at the humanitarian situation in Yemen" and said the pair agreed that a "political solution was ultimately the only way to end the conflict".