Cameron calls for northern European alliance
David Cameron has urged countries across northern Europe to form an "alliance of common interests".
The UK prime minister, who hosted leaders of Nordic and Baltic countries, said they could become an "avant garde" for economic growth.
The PMs of Iceland, Norway, Latvia, Sweden, Finland, Denmark, Lithuania and Estonia are at the London summit.
Mr Cameron said it would boost trade with the countries, currently worth almost £54bn a year.
The government denied the summit was a gathering of EU-wary nations looking for alternative paths, as some critics have suggested.
BBC diplomatic correspondent James Robbins said Mr Cameron's mantra last week had been "Look East", when Chinese vice-premier Li Keqiang was visiting the UK, but now it was "Look North".
"David Cameron says the summit is about opening up the flow of ideas, of trade and investment, particularly in green technology, as well as social policy," our correspondent says.
"But there's a hard political edge as well. Only two of today's participants use the euro: two others aren't even members of the European Union: some see this as the 'Cold Europe' Club of sceptical nations."
Mr Cameron said it made sense for the countries to come together for the benefit of all their economies.
"When it comes to some of the big questions that we're grappling with in Britain today - how we can encourage hi-tech innovation to drive growth, how we can grow our economy without undermining our environment, how we can improve people's well-being - so many of the answers have already been found in the Nordic and Baltic countries," he said.
"This gathering gives us a chance to draw on their expertise. And I hope it will also give the Nordic and Baltic countries a chance to learn from each other, and from us."
Describing himself as a "salesman for British business", Mr Cameron said he hoped the event would produce opportunities to boost trade between the UK and the Nordic and Baltic region which was worth about the same as that with France or China.
On Tuesday, the prime minister signed a partnership document with Norwegian counterpart Jens Stoltenberg, agreeing to work together on oil and gas exploration, the development of offshore wind farms and a North Sea power grid.
Norway is investing £1bn in the Sheringham Shoal windfarm and planning to spend up to £30bn on the Dogger Bank windfarm, which has been licensed for probable construction in 2014 and could potentially supply 10% of the UK's total electricity needs.