Environmental activists have defaced a photo exhibition sponsored by oil giant Shell at the Natural History Museum.
The exhibition was closed for the rest of the day
Protesters smeared oil-like liquid on the entries in a wildlife photography competition in the central hall of the west London museum.
Camp for Climate Action said their aim was to highlight Shell's "attempts to greenwash its reputation".
The museum said it was pleased to work with Shell saying the firm was taking environmental protection seriously.
The exhibition was closed for cleaning after Saturday's afternoon attack and re-opened on Sunday.
Camp for Climate Action is calling on the museum to end its sponsorship arrangements with Shell.
"This is not an attack on the work of the photographers," said activist Dan Baker.
"Shell does not deserve to have its name associated with their beautiful images."
A museum spokesman said no permanent damage had been done to the photographs which are behind a protective glass.
She said: "We fully acknowledge working with an energy company raises difficult questions about the need to balance energy use with the conservation of our natural habitat.
"We are pleased to accept Shell's sponsorship because we believe that Shell is taking a reputable scientific approach to addressing the balance between energy needs and environmental protection.
"We believe that oil companies must be included in any meaningful dialogue about the energy issues facing us all."
Shell has so far made no comment.