A co-founder of the Extinction Rebellion activist group has been arrested a day before he planned to shut down London’s Heathrow Airport. Roger Hallam and another four people were arrested on suspicion of conspiracy to commit a public nuisance. Climate change activists intend to ground flights at Heathrow on Friday morning by flying toy drones in its exclusion area, in protest at global warming and plans to build a third runway at the airport. "Our policing plan is aimed at preventing criminal activity which poses a significant safety and security risk to the airport, and the thousands of passengers that will be using it," said Laurence Taylor of London's Metropolitan Police.<br/> Police had already warned the Heathrow Pause, a group of individual activists with close links to Extinction Rebellion, they faced arrest if they went ahead with their plans.<br/> "In these circumstances, we believe these arrests to be a proportionate response to preventing criminal activity that could significantly impact on a major piece of national infrastructure," said Mr Taylor, a Deputy Assistant Commissioner.<br/> "We remain fully prepared for the planned protest tomorrow, and will work quickly to identify criminal activity and arrest anyone committing offences." Members of the Pause had already said they expected to be detained but would continue with their plans regardless. It is unclear how many of them are. “The pair were just concluding an interview with German news magazine der Spiegel at Billy’s Café in Bethnal Green when four police cars pulled up. Officers handcuffed the Pause activists, placed them in separate cars and drove them away,” Heathrow Pause tweeted. Starting from 3am on Friday, it had planned to fly the toy drones at head height close enough to Heathrow that flights will have to be grounded. The group insists it’s action is non-violent and it has no intention of putting flight safety at risk. "If people come to the airport intent on committing criminal activity they will be arrested," Mr Taylor had said on Wednesday. "Endangering the life of passengers, flying drones without permission within the exclusion zone, attempting to disrupt the airport is very serious. We will enforce the law and we will use legislation available to us ... to prevent that from happening,” he added.