David Cameron is to appear on one of the US's most influential TV shows to "bang the drum for Britain" and encourage Americans to visit or set up a business here, Downing Street has revealed.
The Prime Minister is flying to New York to attend the United Nations General Assembly where he will deliver a keynote speech on Wednesday.
Before the speech he will issue a challenge to world leaders to live up to their promises on aid for developing countries.
But along with his packed schedule of diplomatic work and meetings with fellow leaders, he will go into the studio to record an interview for the Late Show With David Letterman.
Letterman has been a fixture on late-night TV in the US for 30 years, and his mixture of heavyweight interviews and humour including his famous Top Ten lists draws a daily audience of three million or more and frequently creates news headlines with big-name political guests.
Barack Obama has appeared on Letterman seven times, twice since becoming president, most recently using the CBS show last week to deliver a slapdown to election rival Mitt Romney for his comment that 47% of US voters see themselves as "victims".
Cameron will hope to use his appearance on Wednesday to build on the high profile win for Britain by the London Olympics and Paralympics this summer.
Shortly after his arrival in New York, Cameron will call on leaders of rich countries to honour their promises to achieve the UN's eight Millennium Development Goals (MDG) for the developing world, which include eradicating extreme poverty, getting all primary-age children into school, cutting child mortality and improving maternal health.
With less than three years to go to the 2015 deadline, fewer than half of the 142 MDG objectives are on track for delivery, the PM will warn.
He will tell wealthy states that the economic downturn should not be used as an excuse for failing to fulfil their pledges.
"The first thing we must do is send a clear message to everyone who signed up to Millennium Development Goals: that now is the time to step up and honour those promises.
"And I know there are some who say we can't afford to do that right now. They believe we have to focus on ourselves.
"And if that means breaking promises, then they're sorry but it just has to be done. Well I'm sorry but it doesn't," Cameron is expected to say.
"When we make a promise to the poorest people in the world, we should keep it, not turn our back on people who are trusting us to help them.
"More than 5,000 infants die every day from preventable diseases like pneumonia and diarrhoea.
"So to those who say we can't afford to act: I say we can't afford to wait."
Britain has promised to hit the UN's target of devoting 0.7% of national income to aid by 2013 but other wealthy countries like Italy, Japan, the US and Germany are falling well short of that level.
Cameron is co-chairing the first meeting of a UN high-level panel to draw up a framework for international aid after the MDGs expire in 2015, at which he will call for "bold and ambitious" action.
On the eve of the meeting, Cameron agreed in a video conference with his co-chairs, Liberian president Ellen Johnson Sirleaf and Indonesian president Susilo Yudhoyono, that the panel's ambition should be to eliminate absolute poverty and to seek ideas from businesses, civil society and people living in poverty.
The panel is due to submit a report on the way forward for development to UN Secretary General Ban Ki-moon by the middle of next year.
Cameron is also due to meet representatives of New York technology firms, including social media service Foursquare, which are planning to expand into the UK with investment totalling £30 million and are due to create 100 or more jobs in east London's TechCity area within the next few months.
The PM will tell them about government initiatives designed to attract inward investment, including tax breaks for start-ups and special visas for entrepreneurs, as well as the new iCity technology park being developed on the site of the Olympic media and broadcasting centre.
He will also launch a London-NYC Start-Up Awards which will alternate between the two cities annually and recognise excellence in technology innovation.
More:Uk News Millenium Development Goals David Cameron The Late Show With David Letterman United Nations
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