Environmental campaigners have boarded an oil rig as it was being towed out to sea and are staging a protest onboard.

Greenpeace activists say they have scaled the 27,000-tonne Transocean rig on contract to BP – as it attempted to leave the Cromarty Firth sunday night.

The protesters are calling for BP to end drilling for new oil wells and say they are prepared to stay on board the rig “for days”.

At approximately 6.30pm on Sunday night, campaigners in a boat pulled up alongside the rig near Inverness, climbed aboard and unveiled a banner declaring a climate emergency.

Currently occupying a gantry on a leg of the rig below the main deck, the activists want to stop the drilling rig reaching the Vorlich oil field where it is believed to be trying to extract up to 30 million barrels of oil.

Jo, a Greenpeace activist from Scotland who is on board the rig, said: “Warm words flow from BP on their commitment to tackling climate change, yet this rig — and the 30 million barrels it seeks to drill — are a sure a sign that BP are committed to business as usual, fuelling a climate emergency that threatens millions of lives and the future of the living world.

“We can’t let that happen – that’s why we’re here today.

“The Government may be bent on draining the North Sea of every last drop of oil, but this clearly contradicts their climate commitments.

“The perverse idea we must maximise our oil and gas reserves cannot continue.

“That means the Government must seriously reform the Oil & Gas Authority and instead invest heavily in the crucial work of helping oil communities like those in Scotland move from fossil fuels to the industries that will power our low carbon future.”

Responding to the protest, a spokeswoman for BP said: “In all operations safety is our top priority.

“While we recognise the right for peaceful protest, the actions of this group are irresponsible and may put themselves and others unnecessarily at risk.

“We are working with Transocean — the rig’s owner and operator — and the authorities to assess the situation and resolve it peacefully and safely.

“We share the protesters’ concerns about the climate. We support the Paris agreement. And we are working every day to advance the world’s transition to a low carbon future.

“We’re reducing emissions from our own operations – down 1.7 million tonnes last year – improving our products to help our customers reduce their emissions, and creating new low carbon businesses. We are committed to being part of the solution to the climate challenge facing all of us.”

Police Scotland said they were aware of an ongoing incident but that the situation was currently within the jurisdiction of the Cromarty Firth’s Port Authority.

A spokesman for the Port Authority said he was unable to comment at this stage.