Leaders of the Extinction Rebellion climate change protests have threatened to disrupt Britain’s road network with plans for a series of “picnics on the motorway”.

Warnings that the campaign could extend beyond the Easter Weekend came as a pink boat used by activists to blockade Oxford Circus in London was towed away by police following five days at the heart of the demonstrations.

The boat, which became a symbol for the ongoing disruption, was dismantled yesterday afternoon, several hours after Dame Emma Thompson used it as a stage to rally protesters.

Police were initially forced to remove several activists from the deck as dozens of other officers formed a huge line to force back others on the ground. The mast was then dismantled and the boat was towed away to a nearby location as the crowds chanted, “we have more boats”.

A cordon was also placed around the area during the removal. The scene unfolded as the Metropolitan Police said it had made 106 arrests by around 5.30pm yesterday, bringing the total since Monday to 682.

“The serious disruption the demonstrations are causing to people in London and beyond is unacceptable and we completely understand the concern it is causing to those who are disrupted by it,” a tweet said.

Hours earlier Dame Emma, the Oscar-winning actress, arrived in Oxford Circus and gave a speech to crowds from the boat.

She said: “We are here in this little island of sanity and it makes me so happy to be able to join you all and to add my voice to the young people here who have inspired a whole new movement.”

Speaking after to reporters, Dame Emma added: “If you can’t have fun whilst saving the planet, what’s the point? Protest should always have a sense of joy in it because what we are protesting about is saving this extraordinary home of ours and also celebrating the passion and inspiring energy of this young generation.”

But she was also forced to defend her appearance after it emerged she had flown from LA in the US to attend.

Dame Emma insisted she did not fly as much as she used to – and planted a lot of trees.

Earlier, yesterday morning, about 20 activists, most of them under 17, had staged a brief demonstration on roads near Heathrow Airport.

Standing close to a tunnel which leads to terminals two and three, they unfurled a black banner with the message: “Are we the last generation?”

Several police officers watched over the group before an XR spokesman announced before midday there were no further plans to cause disruption at the airport.

All roads remained open during the demonstration, which is part of a two-week campaign that began in central London on Monday.

Waterloo Bridge has now been blocked by demonstrators for five days. Ten people had been charged by the Met by Thursday night and three others arrested by British Transport Police were remanded in custody after they appeared in court accused of obstructing trains at Canary Wharf.

Routes are also blocked around Parliament Square and Marble Arch. Home Secretary Sajid Javid has urged police to use the “full force of the law”.

“I totally condemn any protesters who are stepping outside the boundaries of the law,” Mr Javid said.

“They have no right to cause misery for the millions of people who are trying to lead their daily lives.”

Ken Marsh, chairman of the Metropolitan Police Federation, told BBC Breakfast the protests were “very, very difficult” to handle and could cost “millions”.