THE Prince of Wales and the Duchess of Cornwall are to pay another visit to the United States, it was announced today.

Clarence House said Charles and Camilla will spend two days in Philadelphia and New York on January 27 and 28.

The couple's first joint overseas tour together was to the US in November 2005.

Charles is to receive the Harvard Club's Global Environmental Citizen Award in New York from last year's recipient, Al Gore.

Clarence House described the main themes of the visit as youth development, urban regeneration and environmental conservation.

"The Prince's visit will emphasise the importance which the UK Government places on climate change as a key international priority," a spokeswoman for Charles said.

Clarence House could not confirm whether the Prince and the Duchess would travel to the US using scheduled flights.

"Travel arrangements are still being put in place," a spokeswoman said.

Charles announced sweeping eco-friendly travel plans for his household last month as part of an ambitious green project.

The review also includes examining ways of cutting down on the use of plane and helicopter flights within the UK and using more car and scheduled trains for journeys where appropriate.

In next summer's annual accounts, the Prince will publish details of his own carbon footprint and set a target to reduce the carbon emissions of his office.