Climate change activists who have been massed in a camp near London's Heathrow airport for a week marched Sunday to the site of a proposed new runway to highlight concerns over the impact of aviation on the environment, according to AP. Hundreds have attended the «climate camp» set up in a field north of Heathrow's perimeter fence near the location for a third runway at Europe's busiest airport. After a week of seminars, talks and video presentations, organizers said Sunday would be a day of «direct action». Police said around 1,000 people had gathered at the field. They said small groups of protesters had started to march toward the village of Sipson_ where the new runway is expected to be located, and near to the offices of airport operator BAA. Organizers said that they would not disrupt passenger travel, and called on police to behave proportionately. But there were minor scuffles as police officers ringed the protesters slowly marching along the country lanes surrounding the airport. A fifth terminal is scheduled to open at the airport in March 2008, and the government has proposed the third runway to open around 2020.