Environmental groups including Extinction Rebellion, which has previously staged highly disruptive protests across Britain, have vowed new and "creative" campaigns of disobedience unless the government meets their demands over fossil fuels.
Extinction Rebellion (XR) said the groups had issued the British government with a demand to end all licences, funding and approval for new fossil fuel projects and to immediately create "emergency citizen assemblies".
If the government did not agree to discuss these by a deadline of 1600 GMT on April 24, they would step up their campaigns, which would include unspecified civil disobedience.
"This time we won't be alone," Marijn van de Geer from XR told reporters.
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.
Later this week, some 200 groups including Greenpeace and Friends of the Earth will gather for a four-day demonstration organised by XR, dubbed "The Big One", which will be held outside parliament in central London, with 28,000 signed up to attend.
While 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, van de Geer said they would step up campaigns in future in "new and inventive ways".
She said it would be up to each group and individuals involved to decide what these would be, saying there might be some "bigger disobedience".
(Reporting by Michael Holden, Editing by Kylie MacLellan)
