Climate change activists have threatened to step up campaigns of civil disobedience for months to come - as tens of thousands of protesters are expected to gather in the capital over the London Marathon weekend.
At a press conference on Tuesday, eco-group Extinction Rebellion said it would be joined by allies in the disruption if its demands were not met.
It is calling for the Government to stop the search for new fossil fuels and to establish “emergency citizens’ assemblies” to decide how to bring about the end of the fossil fuel era.
In January, the British arm of XR, which has previously closed key roads and bridges in central London, blockaded oil refineries, smashed windows at banks and thrown paint over government buildings, said it would cease public disruption.
But other activists, such as Just Stop Oil, have continued with high-profile campaigns, including halting the world snooker championship on Monday.
XR issued its ultimatum ahead of “The Big One”, a four-day protest outside Parliament from Friday until Monday, which organisers predict will attract around 30,000 people.
The protest coincides with a busy sporting weekend in London - which includes both FA cup semi finals at Wembley and the London Marathon.
XR said this week’s action in central London was not intended to be disruptive, nor would it target the coronation of King Charles next month.
However, Just Stop Oil, a separate group with similar objectives who are not listed as involved in the protest, has refused to rule out disrupting the marathon and said it expected many of its supporters to be there.
The Metropolitan Police have warned of a “firm” response to the protests and pledged to crack down on demonstrators gluing themselves to roads and buildings in an effort to highlight their cause.
Organisers of the marathon, in which elite athlete Kenenisa Bekele and tens of thousands of ordinary runners will take part on Sunday, advised spectators to avoid Parliament Square because it will be “very busy”.
Hugh Brasher, the race’s event director, said: “The Extinction Rebellion organisers have assured us that they do not wish to disrupt the TCS London Marathon. ”
Marijn van de Geer, of XR, told a press conference: “From today, we are putting the Government on notice.
“They have seven days to agree to enter negotiations around these two demands or we will step up our campaigns in new and inventive ways, working towards a coalition unprecedented in size.”
She said the Government has until 5pm on Monday April 24 “to agree to enter negotiations about the two collective demands that we have presented to them today”.
Ms van de Geer added: “If we don’t get a response, at 10am on Tuesday April 25 Extinction Rebellion will build an unprecedented coalition, stepping up our campaigns in the weeks and months ahead along three pathways - that is to picket to stand in solidarity with the strikers, to organise locally and to disobey.”
More than 200 organisations are supporting the “The Big One” action, including Greenpeace, Friends of the Earth and PCS Union, XR said.
Ms van de Geer said: “We’ve come back stronger than ever, with unions, NGOs, ethical companies and a whole host of environmental groups all united in our call for political change and action to protect all life on Earth.”
She said “The Big One” will “be a period of connecting and music and dance but also it is a four-day coming together of over 200 groups with memberships totalling millions of people in this country and globally to decide what more radical action would look like for them”.
She added: “So across these four days everyone will deliberate on what comes next if the Government refuses this major opportunity to engage with our demands, because we all agree the clock is ticking for every human and non-human alive today and none of us should and will sit quietly while time runs out.”
More than 28,000 people have signed up to attend during the four-days of protest but XR believes the turnout may be higher, Ms van de Geer said.
Ms van de Geer added: “Of course, having 30,000 people in the Westminster area may cause some logistical disruption, and there is of course also the London Marathon happening as well, so it is going to be nice and busy in central London over the weekend.”
A Met Police statement said: “The Met is aware of planned protests by Extinction Rebellion this weekend.
“We are in contact with the organisers in the run up to their event, and will continue to engage with them throughout the period, in an effort to avoid serious disruption and delays to London’s communities and the other events taking place in London. However, we have a policing plan in place to provide an appropriate response to the protest.
“People can expect a visible, engaging but firm policing presence to tackle any criminal or anti-social behaviour and disorder. Alongside a significant policing response we will be using specialist officers to respond to any protesters who lock or glue themselves to street furniture or purpose built structures.”
