Scotland, Wales and Northern Ireland should spend their tourism budgets on promoting London if they want to attract more visitors, according to the capital's deputy mayor.

The countries are in danger of "cutting off their noses to spite their faces" by continuing to compete against London for visitors, Kit Malthouse told the Observer. They should instead recognise the reality of London's pre-eminence, help to promote it further and, in return, the UK's capital would educate visitors about the benefits of going for "a few days up to Edinburgh or to Cardiff or to Belfast".

Malthouse, who was appointed by mayor Boris Johnson this summer as chairman of London & Partners, the capital's official promotional organisation, conceded that his argument was a "very, very hard sell", but said that the UK should build on its strengths. "All we have to do is lay down the territoriality and recognise that we can all win out of this," he said. "The overall spend of all bodies in the country is about £144m. That is a combination of money from regional governments and we get our £9.4m from the mayor.

"If you look at Scotland and their £44m, some of that comes from central government, some from the Scottish government. We think that if more of that was spent on London-plus strategy, then Scotland, Wales and Northern Ireland would win a lot more overall.

"We are quite happy with them keeping control of the budget, but what we would love to do is agree joint marketing campaigns. So I suppose what we would be asking Scotland to do would be to spend some of their money promoting London as part of a London plus Scotland campaign."

His comments are unlikely to go down well in Edinburgh, Cardiff and Belfast, but reflect a growing confidence in the strengths of the capital as it comes out of the economic downturn more rapidly than the rest of the UK.

A recent forecast by the Centre for Economics and Business Research suggests that London's gross domestic product will expand by an average annual rate of 1.9% between this year and 2018 – compared with a more pedestrian 1.4% for the UK as a whole.

It is understood that Malthouse is due to have meetings with tourist boards from across the UK in the coming weeks to convince them of the benefits of his London-plus strategy. Rather than exacerbate a north-south economic divide, Malthouse said that by using London as a "honeypot to bait and tempt people", the whole UK would benefit. "We know, for instance, that well over half – approaching two-thirds – of the people who come to the UK and who go to other parts of the UK wouldn't come if it weren't for London.

"When you look at the pattern of tourism spending for the various regions, London comes bottom of the table. And we think that is getting [the] thinking about-face. We spend about £9m on tourism. Next [largest] after that is Visit England, which spends about £11m – London is a big part of that. Wales spends £12m; Scotland £44m; Northern Ireland £30m; Visit Britain overall spends £36m. So we are way at the bottom and, given that London is the gold standard for tourism and the main reason the vast majority of tourists come to the UK, we think we will miss a trick as a nation as a whole if we don't shove it out there and, as I say, point out that you can get to Edinburgh in under three hours."

Malthouse, a Tory member of the London assembly and former deputy leader of Westminster city council, said he expected resistance to his message, but that the figures made a convincing case. "It is a very, very hard sell, but in the end we have to be careful that we are not cutting off our noses to spite our faces. There are many areas in which the regions, including London, compete in a futile way, and this is one of them."