Theresa May has defended the UK's relationship with Saudi Arabia ahead of trade talks in Riyadh where she hopes to boost Britain's post-Brexit business ties.
In recent weeks the prime minister has faced widespread criticism over Britain's arms deals with the Arab state.
There have also been repeated calls to suspend the sales of weapons amid claims of human rights abuses in Yemen under the Saudi-led coalition bombing campaign.
But Mrs May stressed how important UK-Saudi business dealings were for the "safety and prosperity" of the country.
She told ITV News: "Our relationship with Saudi is very important to the United Kingdom. It's a long-standing one.
"We have cooperated on trade, but also on security, helping to maintain security of the region, but also the security of the United Kingdom. It's in the British national interest."
Asked about alleged human rights abuses by the country, Mrs May said it was an issue she would bring up and pledged Britain would continue supporting the people of Yemen through humanitarian aid.
"I think it's important not to stand on the side lines and not just talk about these things, but actually engage to make a difference."
Mrs May's visit to Saudi Arabia has been met with criticism from the Labour party amid continuing questions over the nation's human rights record and whether or not Britain should be providing them with arms.
Opposition leader Jeremy Corbyn called on the PM to put the issue of human rights at the centre of her talks with Saudi leaders.
He said: "Unless the prime minister challenges the Saudi regime over its abuses this week, it will be clear she is ready to sacrifice human rights and security on the altar of the arms trade.
"The Saudi-led coalition bombing in Yemen, backed by the British government, has left thousands dead, 21 million people in need of humanitarian assistance and three million refugees uprooted from their homes.
"Yemen urgently needs a ceasefire, a political settlement, and food aid, not more bombing."
Mrs May's Saudi visit is part of the second leg of her Gulf Tour.
She has already visited Jordan, where she announced UK military trainers will be sent to the country to help the nation's air force in the fight against the so-called Islamic State.