Global St Patrick's Day celebrations will take a twist this year with some of the world's most iconic buildings turning green.

Tourism bosses have revealed New York's Empire State Building, the London Eye, the Sydney Opera House and the CN Tower in Toronto will all be seen in a new light on March 17.

Niall Gibbons, Tourism Ireland chief executive, said the colourful ad campaign was a major coup.

"The agreement to allow us to 'green' such iconic buildings and attractions must be a first for any destination and clearly illustrates the goodwill that the Ireland brand generates across the world," he said.

"We will use every opportunity to capitalise on Ireland's heightened profile to showcase the uniqueness of a holiday on the island - the diversity of our culture and heritage and the friendliness of our people."

The tourism boss said it was a unique chance to showcase Ireland to an audience of 70 million people who claim links to the island.

The one-off greening is the highlight of the biggest ever worldwide promotion of Ireland in the run-up to St Patrick's Day.

The €1m investment targets visitors from Britain, Europe, North America, Australia and new markets such as China, India and South Africa.

Mr Gibbons said there will also be saturation coverage of Ireland on the airwaves, newspapers and digital media.

"We aim to bring a smile to the world. The message is that there has never been a better time to visit the island of Ireland," he said.