Extinction Rebellion protesters on the streets of London have been labelled "uncooperative crusties" by Prime Minister Boris Johnson. The demonstrators - who are demanding action on climate change - should abandon their "hemp-smelling bivouacs" and stop blocking roads, the PM added. Police have already arrested more than 300 people at the start of two weeks of protests by environmental campaigners. Some activists glued themselves to government buildings early on Tuesday. Speaking at a book launch, Mr Johnson said: "I am afraid that the security people didn't want me to come along tonight because they said the road was full of uncooperative crusties and protesters of all kinds littering the road. "They said there was some risk that I would be egged." Mr Johnson added protesters could learn from former PM Margaret Thatcher, who he said had taken the issue of greenhouse gases seriously long before activists such as Greta Thunberg were born. "I hope that when we go out from this place tonight and we are waylaid by importunate nose-ringed climate change protesters, we remind them that she was also right about greenhouse gases." Extinction Rebellion activists are protesting in cities around the world, including Berlin, Amsterdam and Sydney. The Metropolitan Police said there have been 319 arrests in relation to the demonstrations since 00:01 BST on Tuesday. Some 200 campaigners who camped overnight on streets in central London also faced arrest on Tuesday morning after being issued with warnings by police. Activists who blocked Horseferry Road, in Westminster, throughout the night were warned that they will be arrested unless they move to nearby Trafalgar Square. But many said they were prepared to stay in the camp. Mike Gumn, 33, from Bristol, told the PA news agency: "We will decide as a group when we are going to move and we are not going to let police tell us when."