Insulate Britain protesters have ink thrown on them as they block roads near Dartford Crossing and the A40 in North Acton

Watch: Man squirts Insulate Britain protesters with ink as they block roads

Insulate Britain protesters have had ink thrown over them as they blocked part of the A40 in west London and a roundabout near the Dartford Crossing.

It's the latest action by the group, who've also blocked roads in central London and the M25 in recent weeks.

One protester, pictured below with the dye-like substance on his face, said: "It's sad that we have to do this, I hate doing it.

"I'm a retired doctor and I've spent my life trying to help people and I'm reduced to having to do this."

Asked if he was worried about violence from the public, he said "of course, terribly worried".

But he said he had to take action because the government was not addressing the climate problem adequately.

Metropolitan Police said it was looking into a report of common assault in relation to a "substance believed to be ink" thrown at protesters in Acton.

It said no arrests had been made so far.

Insulate Britain is calling for the government to fund the insulation of homes in order to reduce emissions and fight climate change.

Wednesday morning's protests were near Gypsy Corner on the A40 in North Acton, where cameras showed people sitting in the road in front of queuing traffic.

There was another near the Dartford Crossing in Kent, at the A206 Crossways Boulevard, and on a slip road for junction 1a of the M25.

Sky News reporter Katie Barnfield said police in Acton used syringes of solvent to free the final protester - a man who had glued his feet to the tarmac - before arresting him and reopening the road around 10am.

Watch: Police arrest Insulate Britain protestors in Dartford

In Kent, police said that 32 people had been arrested, with a few detained in a nearby car park.

It said officers were on the scene minutes after receiving reports of the protest - including that some people had "glued themselves to the road surface, or each other".

It comes as the group also asked drivers to avoid the M25, or reduce their speed to 20mph, declaring the motorway is now "a site of nonviolent civil resistance to stop our government committing crimes against humanity".

Insulate Britain confirmed its members were behind this morning's disruption and said it was the fifteenth time it had blocked roads in the last six weeks.

It comes despite a new "super injunction" that bans the group from interfering with traffic on any part of the road network in England.

One member of Insulate Britain, Suzie, 47, from Cambridge, said: "If going to prison and losing my home is what it takes to get the government to do the right thing and cut our carbon emissions then it's a price worth paying.

"I can't be a bystander while this government betrays the public, our children and future generations by failing to defend our country from the climate crisis."

The latest protest comes two days after police in central London arrested 53 people after the group restarted its campaign following a 10-day break.

Video from Monday showed one man berating protesters, saying his father needed treatment and calling them "scum" - and even wishing cancer on the family of one protester.

Some activists have glued themselves to the road during the sit-ins, and there have also been instances where members of the public have dragged them out the way.

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The group confirmed to Sky News that "someone threw" the ink over the people sitting in the road on Wednesday morning.