Prime Minister David Cameron has defended his decision to fly to the Gulf to promote British defence exports to countries that have been criticised over human rights.
Mr Cameron said he made "no apology" for helping Britain's defence industry do deals abroad.
His comment is set to be delivered in a high-profile Mansion House speech in the City of London, where the Prime Minister is due to unveil plans to boost UK exports to growing economic markets around the globe.
The annual speech is traditionally the Prime Minister's highest-profile foreign affairs address of the year. But rather than talk about the crises in Syria or Iran or the row over the EU budget, Mr Cameron is expected to spell out his argument that the Government should use its clout abroad to help British companies win the "global race" for jobs and business.
Mr Cameron came under fire last week for his three-day tour of the Gulf, in which he hoped to help sell 100 Typhoon jets - worth a total of £6 billion to the UK - to the UAE, Saudi Arabia and Oman.
He will accept that some people are "squeamish" about the human rights records of some of the region's governments. But he will insist that Britain has the toughest arms export rules in the world to prevent weapons being misused.
Mr Cameron will say: "We must support all sectors of the economy where we have a comparative advantage - and that includes defence. I understand why some people are a bit squeamish about me flying off round the world to help our defence industry do deals abroad. But let me say this. Britain has the most rigorous arms export licensing regime in the whole world - and that is how it will stay.
"But there is a more fundamental point here. Every country in the world has a right to self-defence. And you cannot expect every country to be self-sufficient in providing the tanks, ships and planes needed.
"So when Britain has a very strong defence industry, with 300,000 jobs depending on it, it's right that we should be at the forefront of this market, supporting British jobs and British allies, and that's why last week, in the Gulf, I was pushing for new contracts for Typhoon jets worth billions of pounds and thousands of jobs.
"That's vital new business for Britain. And I make no apology for going out there and trying to help win it."