A number of climate change campaigners have taken to trees in Parliament Square as part of the ongoing Extinction Rebellion protests.
At least four people have scaled the trees to install hammocks, taking their protests to new heights.
The development came as thousands of their colleagues marched from Marble Arch - the centre of the 'legal' protest - to Parliament Square in Westminster.
The tree protesters could be seen lowering ropes to the ground where waiting supporters tied bags - presumably full of supplies - which were then hauled back up to the canopy above.
Rachael Brown, from ITV News, reported that police had cordoned off the area below the trees.
Police have said they have a “robust” plan in place ahead of a proposed climate change protest in Parliament Square.
The demonstration on Tuesday – which coincides with the first day Parliament is sitting following the Easter recess – is the latest action by Extinction Rebellion protesters in the capital.
Among the campaigners’ demands is for the Government to declare a climate emergency, and members of XR have previously suggested temporarily ending disruptive tactics to focus on political negotiations as the campaign enters a second week.
Activists walked from Marble Arch to Parliament Square on Tuesday morning, arriving outside Parliament.
Scotland Yard has said protesters at Parliament Square must leave a designated area by 11.59pm on Tuesday and warned: “Any organiser or person taking part in the protest failing to comply with these conditions or inciting others not to comply with them will be committing an offence and will be liable to arrest.”
The force added: “A robust policing plan will be in place for the demonstration.”
More than 1,000 people have been arrested during the climate change protests which started on Monday April 15.
The action has seen Waterloo Bridge and Oxford Circus blocked and a “die in” at the Natural History Museum.
Meanwhile, Swedish schoolgirl Greta Thunberg, who has inspired international youth climate strikes, has met part leaders in the House of Commons.
Labour leader Jeremy Corbyn, Green MP Caroline Lucas, and the Westminster leaders of the Scottish National Party and Plaid Cymru, Ian Blackford and Liz Saville Roberts attended.
Noticeably absent from the meeting, however, was Theresa May, with an empty chair and a nameplate on the table.