Two more campaigners have boarded a BP oil rig just hours after police were drafted in to end the protest.

Greenpeace first pulled up in a boat alongside the rig in the Cromarty Firth, near Inverness, on Sunday evening before protesters climbed aboard and unveiled a banner declaring a climate emergency.

Nine people have been arrested since the protest began, with another two campaigners now on board the rig, which was due to be towed to the Vorlich oil field east of Aberdeen.

Greenpeace are calling on BP to halt new drilling for fossil fuels.

John Sauven, executive director at Greenpeace UK, said: "Our climbers are back on the oil rig and determined to stay for as long as possible.

"BP are heading out to drill a new well giving them access to 30 million barrels of oil - something we can't afford in the middle of a climate emergency.

"We can't give up and let oil giants carry on with business as usual because that means giving up on a habitable planet and our kids' future.

"The UK government has announced a target of net zero greenhouse emissions by 2050 - we have started to enforce it."

A helicopter and boats were used by police to try to end the occupation on Thursday after the rig's owner Transocean obtained an interdict to remove the activists.

BP described the group's latest actions as "irresponsible".

A spokesman said: "BP supports debate, discussion and peaceful demonstration, but the irresponsible actions of this group are putting themselves and others unnecessarily at risk, while ignoring court orders and police action."

A Police Scotland spokesman said: "Police Scotland continues to work with the operators of the installation, the Cromarty Firth Port Authority and other interested parties to achieve a safe resolution to the continuing protest in the Cromarty Firth."