Green-faced extra-terrestrials with bouncy antennae wandered through the UN global warming talks in Copenhagen to the Japanese delegation on Thursday where they demanded: "Take me to your climate leader."

The visitors -- activists from environmental group Avaaz.org -- staged the stunt ahead of a government decision in Tokyo on setting Japan's contribution to a fund to help poor nations badly exposed to climate damage.

Under the gaze of bemused Danish security guards, the "aliens" were admitted to the delegation office where they explained they had come to deliver a warning from Planet B, a world destroyed by climate change.

"We have been searching all month for climate leaders, and today Japan is looking like our best hope," said a costumed E.T.