Russia has dropped piracy charges against 30 people involved in a Greenpeace protest over Arctic oil drilling.

Russian media agencies reported that prosecutors have replaced the piracy charge with the lesser charge of hooliganism.

The charge of piracy carries a maximum jail sentence of 15 years.

Greenpeace had said last month's protest was peaceful and it dismissed the piracy charges as absurd and unfounded.

The activists were arrested after the Greenpeace ship Arctic Sunrise approached a platform belonging to state-controlled energy firm Gazprom.

It was reported that two activists tried to scale the platform.

The 30 activists have been held in custody in the northern Russian city of Murmansk.