The unnamed industry boss told The Times that although the capital had “carried on doing well” after the Westminster attack in March, tourism in Paris – which has suffered a string of attacks in recent years – had declined due to the ongoing incidents.

The source said they expected to see similar results with tourism in London following Saturday night’s attack which targeted tourists on London Bridge and in Borough Market and left seven people dead and 48 injured.

They said: “London carried on doing well after Westminster, as overseas visitors had already booked and the weak pound acted as a draw, but we face a dip in business of four to five months. Paris tourism was down 30% and I’m expecting something similar in London.”

Nick Varney, chief executive of Merlin Entertainments, which operates Madame Tussauds and the London Eye, insisted that the capital’s long-term growth remained intact.

“We’ve seen this before and what happened at London Bridge is terrible, but more than any other city London has shown its resilience and ability to bounce back,” he told the newspaper.

“It remains a long-term successful growth story for tourism because it’s a unique world-class destination, but there’s no getting away from the fact that this is going to affect businesses in the tourism and hospitality trade in the short term.”

Although Mark Brumby, leisure analyst at Langton Capital, suggested international visitors may be wary of holidaying in London, he said: “Mums will be telling daughters not to go out, while Kiwi, Aussie and other parents will be suggesting their kids give London a miss.”

Simon French, an analyst at financial consultants Cenkos, added: “A small number of domestic and overseas visitors will be deterred, but we expect footfall in London and other major UK cities to remain robust.”