Loach, famous for films like My Name is Joe, Raining Stones and Riff-Raff, is in Cannes for a special screening of his film Kes, which was made in 1969.
Loach's comments could hit a raw nerve this year, as no British films have been shortlisted for the prestigious Palme d'Or.
He told BBC Radio 4's Today programme: "The climate generally in Britain is to make films that look across the Atlantic and I think that's disastrous."
"It means our own culture gets devalued and it's as though there has to be an American in everything."
Loach said that British films and many directors use British films as calling-cards for the states.
"I think it's time British film-makers stopped allowing themselves to be colonised so ruthlessly by US ideas and stopped looking so slavishly to the US market," he said, adding that it "demeans film-making when they do that".
Ironically, his latest film, Bread and Roses, was made in Los Angeles, but Loach insisted it was a "very anti-Hollywood film".
He said it was a story of the people who clean the offices in LA.
'Hostile'
"There is a nice irony in making a film in LA about that half of the people you don't see - that aren't represented - they're the ones who do the work really," he said.
"Their lives are as full of drama and comedy - much more so really - than the white people who live in the hills."
But despite dipping his toes in US waters, he imagined it will be his last film in America.
"It's a fairly hostile place to be in - probably the most difficult place in the world to make films, oddly enough because they have very fixed ways of doing things," he said.
Meanwhile, in Cannes, tension is mounting over which film will win the Palme d'Or prize - awarded to the year's best feature film.
Shrek, DreamWorks' animated movie about a lonely ogre is being hotly tipped, after getting its official première at this year's event.
The gentle fairytale which features the voices of Canadian star Mike Myers, comedian Eddie Murphy and actress Cameron Diaz, is only the fifth animated film to be entered for the prize.
It is the first US animation since Peter Pan first charmed the movie world 50 years ago.
Producer's prize
But not everyone has to wait until the end of the festival for the prize - Pulp Fiction producer Lawrence Bender became the first non-European to win Cannes' producer of the year.
Cannes' programmer Veronique Cayla said Benders' "history is so linked to that of the festival", and she saluted him for "proving to Hollywood you can attract viewers to auteur films".
Bender joked that the prize, which is essentially a lifetime achievement award, had come "a little early in the career, but I'll take it".
About 60 well-wishers gathered in the Cafe des Palmes Sunday at noon to attend the ceremony for the US producer, who is also famed for Reservoir Dogs.
Quentin Tarantino, who shot to fame after directing 1994 box-office hit Pulp Fiction, said Bender's attention to details means "Lawrence produces the movie as if he were (the) director".
Tarantino said that if Bender, born in 1958, seems too young to get the festival's third such salute, "dealing with my silly ass deserves a lifetime achievement award, trust me".
And Miramax Films co-chairman Harvey Weinstein said his studio is sometimes referred to as the House That Quentin Built, "but Quentin's house was built by Lawrence", he added.
Bender also produced The Mexican, Jackie Brown, Good Will Hunting and From Dusk Til Dawn.