Expansion plans for Heathrow Airport have divided MPs
Campaigners opposed to the government's approval of a third runway at Heathrow vandalised glass doors at the Department for Transport in London.
A group called the Climate Suffragettes said three of their members hurled bricks and green paint at the office in the early hours of Friday.
A spokeswoman for the group said: "The government has opened the floodgates for radical action."
A spokesman for the department said police are investigating the vandalism.
The incident happened at the department's office in Great Minster House in Westminster, central London.
'Spat at democracy'
The Climate Suffragettes, part of a group called Climate Rush, say three women wearing red sashes threw the bricks that were wrapped in papers reading: "No third runway, the Suffra-jets are back".
A spokeswoman said: "Yesterday they sacrificed all of our futures and spat in the face of democracy. The third runway is unwanted and is a global threat."
The protest came a day after Transport Secretary Geoff Hoon announced that the third runway was being given the go-ahead.
Residents and environmental campaigners have vowed to continue protests against the expansion plan, but Mr Hoon said the business case for more capacity at the airport was compelling.
Business leaders warned that London's - and Britain's - competitive advantage in Europe would be compromised if capacity at the airport did not increase.
Up to 700 homes will be demolished to make way for the runway, to allow Heathrow's flight capacity to rise from 480,000 to 702,000 per year.
Environmental campaigners have also said the decision leaves the government's legal commitment to cut carbon emissions by 80% by 2050 in tatters.
However, the government said the plans represent "constrained expansion" with strict controls on noise and air quality.