Greenpeace says six of its environmental activists are attempting to scale Western Europe's tallest building to protest drilling in the Arctic by oil companies.

The group said the six climbers, all women, hoped to affix an artwork to the top of the 310-meter (1,017-foot) tower known as the Shard.

Greenpeace says the climbers are from Britain, Canada, Sweden, Poland, the Netherlands and Belgium.

It says the Renzo Piano-designed 72-story Shard had been chosen because it looms over the London offices of Royal Dutch Shell.

London's Metropolitan Police Force says officers are monitoring the situation.