Greenpeace said its activists remain in their position on an oil rig which was being towed out to sea, despite police attempts to remove them.
Campaigners from the environmental organisation have been occupying the rig in the Cromarty Firth, near Inverness, since Sunday evening.
They are calling on BP to stop drilling for oil and hope to stop the drilling rig from reaching the Vorlich oil field where it is believed to be trying to extract up to 30 million barrels of oil.
Greenpeace said that on Thursday a police helicopter was seen landing on the rig’s helideck, dropping off a group of police officers in climbing gear.
The organisation said that rig operators then started lowering the structure into the sea to bring the climbers closer to the water’s edge.
Greenpeace said that two police boats then approached the rig while police climbers approached the activists from above and removed a banner reading “climate emergency” from the gantry.
The activists are occupying a gantry on a leg of the 27,000-tonne rig below the main deck.
Police said it remains an “ongoing incident”.
Responding to the protest earlier in the week, 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.”