The huge garden, which was inaugurated in 2010 but was only certified as a record this week, was designed by architect Francesco Bollani who headed up a creative team that included an architecture studio from Montpellier in France.

"It took us a year to grow the plants in a greenhouse and 90 days to build the facade," Bollani told AFP. "It was like building a giant Lego!"

The previous record was held by a Madrid garden covering 844 square metres.

Shopping centre director Simone Rao said: "This is sustainable architecture, which can combine beauty with energy saving while respecting the environment."

The garden helps regulate the temperature in the shopping centre in Rozzano and, by reducing direct sunlight, it helps keep energy consumption low.

It also absorbs carbon dioxide and reduces ambient noise to a minimum.

French architect Le Corbusier was one of the first to conceive of a vertical garden in 1923 and the idea has become very popular in architecture circles.

Bollani said that his version was easier to build and take apart because the garden is made up of small metallic containers.

This means the garden is more expensive than classical methods, with a total cost of 1.0 million euros ($1.3 million), he said.