Environmental campaigners targeted an Oxford-based 'carbon-offsetting' company yesterday as part of a protest against air travel.

Activists from the Climate Camp and Plane Stupid groups arrived at the offices of Climate Care, in Magdalen Road, East Oxford, at 9am.

The protesters had been involved in action at Heathrow Airport over the weekend and their stunt mirrored three similar incidents in other parts of the country.

Some of the group climbed on to a first-floor roof before unveiling a banner which read 'Carbon Offsetting = Red Herring'.

Campaigners dressed as red herrings also waved placards outside the office. It is thought between 15 and 20 people were involved in the action.

During the protest, activists and Climate Care managers met inside to discuss the issue.

Plane Stupid spokesman Joss Garman said many of the people involved in the action had taken part in the demonstration against the British Airports' Authority's planned expansion at Heathrow.

Mr Garman said: "We want to highlight to members of the public who give money to Climate Care that it does not neutralise the impact on the environment.

"Paying people in developing countries to pollute less so we can pollute more is not a responsible solution to climate change."

Michael Buick, of Climate Care, said carbon offsetting was important as part of a range of measures to tackle carbon emissions.

He said: "The point is one of principle. The campaigners do not think it is acceptable to take responsibility for your impact on the climate by paying for offsets.

"There is no 'green' flight option, but what you can do is say 'I will avoid flying if I can and if I can't I will pay for the offset'.

"From our experience, people are doing it as part of reducing their impact, not as an excuse."

Thames Valley Police attended the protest, but a spokesman for the force said no arrests had been made and the demonstration, that ended at 11.15am, had been peaceful.

*Climate Care is one of a number of companies that allows individuals and businesses to 'offset' carbon emissions.

People can calculate the size of their carbon footprint using an online calculator and then pay for that to be offset by investing in renewable energy, energy efficiency and reforestation projects.

According to the Climate Care website two people taking a return flight from Heathrow to Mallorca produces 0.62 tonnes of carbon and would cost £4.62 to offset.

Projects supported by Climate Care include a wind farm in India, providing energy efficient lightbulbs in schools in Kazakhstan and reforestation in Uganda.