The standard of French cuisine is on the slide, the head of the authoritative La Liste ranking has said, despite a Paris restaurant being declared the best in the world for the third year running.

Beyond the top gastronomic hot spots, the level of cooking was sometimes “lamentable” said Philippe Faure, a former French diplomat who also heads the country’s tourism promotion council.

“Thirty or 40 years ago you could cross the country stopping randomly every 20 kilometres and eat very well; there were good bistros everywhere. But that is no longer the case,” he told AFP. “Without using a guide you can now eat better in Switzerland, Spain and in Italy,” he added, when it used to be “the other way around”.

Faure said that while high-end French gastronomy was thriving – with Guy Savoy’s riverside restaurant in Paris ranked the best in the world alongside French-born Eric Ripert’s Le Bernardin in New York – it has “not succeeded in pulling up the rest”.

“There are too few [good] gastronomic bistros in the big towns and not enough young people doing good things. In the provinces it’s lamentable, it’s not good,” he said.

The claims come three years after the French-based La Liste was set up as a scientific counterweight to the British-based 50 Best Restaurants guide, which had long been accused of “French bashing”.

La Liste’s “guide of guides” ranks the 1,000 best restaurants in the world by aggregating millions of reviews from guides such as Michelin, newspapers and websites such as Yelp and TripAdvisor.

Faure said that while haute cuisine is still regarded as the best in the world, with a revival in traditional French cooking in the US, more humble French restaurants were struggling abroad. That was also because French cooking was more demanding and needed greater technique, he said.

“Fifty to 100 French restaurants were closing every year in Japan [when he was ambassador there in 2011] while 200 Italian ones were opening. Italian cooking is very easy,” he said. “You can’t go wrong. Pasta, conserves, sundried tomatoes and parmesan cheese keep for years.

“But in a French restaurant you have to have fresh salads, fresh fish sauces, delicate fine cheeses and that is infinitely more complicated and costly and it demands a lot of knowhow,” he said.