Professor John Lennon, director of the Moffat Centre for Travel and Tourism Business Development at Glasgow Caledonian University, dismissed Malthouse's argument as "bizarre," arguing it was not based on any sound evidence.
Malthouse - appointed by mayor Boris Johnson this summer as chairman of London and Partners, the city's official promotional organisation - said Scottish, Welsh and Northern Irish tourist chiefs should spend money on promoting London to attract more visitors.
He argued the countries were in danger of "cutting off their noses to spite their faces" by continuing to compete against London for visitors. Malthouse said more of Scotland's £44 million tourism budget should be spent on a "London-plus strategy" - a joint marketing campaign.
In an interview with the Sunday Herald, Lennon, who is also vice-dean of Glasgow School for Business and Society, called Malthouse's ideas "flawed" and "weird".
He said: "The reality is, London is the gateway for the UK, the majority of tourists do come in through its three or four main airports. However, to not promote Scotland as a distinct identity and a brand, and to focus on London solely would be flawed to say the least.
"Scotland is full of universal icons that are internationally recognised and to not undertake marketing based on the established and well-known brand icons we have would be foolish in the extreme. The idea that we would take a budget devoted to focusing on national [Scottish] marketing and move it to focusing on the capital of another country in the UK, would be weird."
Figures from VisitScotland revealed that 57% of the 2.2 million overseas visitors who come to Scotland stay only in this country, arrive directly, and do not go to London.
Clare Gemmell, manager of West Dunbartonshire-based tourist attraction Loch Lomond Shores, said: "Clearly a cohesive UK tourism strategy is important but diverting Scotland's marketing budget to London in return for a vague promise that visitors will be sent 'up to Edinburgh' for 'a few days would be unreasonable.
"Loch Lomond Shores has enjoyed a phenomenally successful summer thanks in no small part to the money and effort which goes into promoting both Loch Lomond and Scotland as brands."
A spokesman from London and Partners failed to reply to Sunday Herald requests for comment.