GREENPEACE director Kumi Naidoo will fly to Peru tomorrow to apologise for the group’s stunt at the world-famous Nazca lines, which Peruvian authorities say harmed the archaeological marvel.

“We fully understand that this looks bad. We came across as careless and crass,” a Greenpeace statement said.

A senior Peruvian official had said that his government would seek criminal charges against Greenpeace activists for damaging the lines.

Greenpeace had intended Monday’s action to promote clean energy to delegates from 190 countries at the UN climate talks in nearby Lima.

But it acknowledged in the second of two emails on Wednesday that it recognised how deeply it had offended many Peruvians. Greenpeace said that it will fully co-operate with any investigation and is “willing to face fair and reasonable consequences.”

The activists’ stunt involved laying a clean-energy message beside the figure of a hummingbird comprised of black rocks on a white background.

Deputy Culture Minister Luis Jaime Castillo said that no-one, not even presidents and Cabinet ministers, is allowed without authorisation where the activists trod and those who do have permission must wear special shoes.

The Nazca lines are huge figures depicting living creatures, stylised plants and imaginary figures scratched on the ground between 1,500 and 2,000 years ago. They are believed to have had ritual astronomical functions.

Greenpeace delegation leader Martin Kaiser said that none of the people involved in the action had been arrested.