Paris officials have come up with an eco-friendly way to keep the city's grass trim - by enlisting hungry sheep to replace gas-guzzling lawnmowers.

The initiative, which started this week, sees four sheep from an island in Brittany put to work munching the bountiful grass of the Paris Archives.

The eco-experiment, which could expand around the capital from October, follows on from a stint last year by two goats that the Louvre hired to mow the lawn of Paris' famed Tuileries gardens.

Already, private companies have hundreds of operational sheep mowing lawns of big companies around Paris.

"(It') efficient... and cheap," says Paris City Hall's Fabienne Giboudeaux. "I can imagine this very easily in London. And New York... even Tokyo."