The Queen commences a compassionate visit to the US on Thursday to meet survivors from the Virginia Tech college shootings in what will be her first trip to the US in 16 years.

|PIC1|The Queen will be joined by the Duke of Edinburgh on her six-day tour, which will conclude with two days in Washington DC to meet US President George Bush, and will involve cementing relations between Britain and the US on building a shared future, the BBC reports.

On Thursday, the Queen is expected to meet survivors and family members of victims of the Virginia Tech massacre, the worst-ever college shooting in US history, and will address the Virginia assembly with a keynote speech at the state capitol.

The visit will be the fourth official state visit to the US by the Queen, with previous tours coming in 1957, 1976 and 1991. The Queen also visited Ronald Reagan in 1983.

In efforts to tackle climate change, the visit will be the first to implement new measures that will offset the carbon emissions caused by her trip.

The visit will be the first to subscribe to the green scheme known as offsetting your carbon footprint.

A Buckingham Palace spokeswoman has said: "Discussions with the Department of Transport have been going on for some time. This is the first time one of the Queen's official visits will have a carbon offset. The figure is still being calculated."

The offsetting bill - expected to be around £5,000 - will be paid by taxpayers through the annual grant-in-aid paid to the royal family to cover the cost of travel on official engagements.

The spokeswoman added: "The Prince of Wales's views brought it into focus. It's public money so it must conform to carbon offsetting in terms of government policy."