BANGKOK, Aug 15 (Reuters) - Thai police clashed with protesters near the residence of Prime Minister Prayuth Chan-ocha on Sunday for a fifth time in the past week, with officers using water cannon and teargas against demonstrators hurling projectiles towards them. A separate "car mob" convoy of thousands of cars and motorcycles urging Prayuth to resign amid anger over his government"s handling of the COVID-19 pandemic had earlier passed through Bangkok peacefully. But once again the anti-government protests of recent weeks resulted in violent clashes in front of Prayuth"s residence. Authorities say public gatherings are illegal under the COVID-19 emergency. One of the organisers of the so-called car mob, Nattawut Saikua, a veteran political activist, went to the site of the clashes to urge protesters to head home. Thailand"s youth-led anti-government protest movement appears have regained momentum and its support has broadened after demonstrations last year attracted hundreds of thousands of people before a crackdown by the authorities. Other political groups, including some of Prayuth"s former allies, are now joining the protests as the country struggles to cope with its worst wave of COVID-19, with many blaming the government"s handling of the crisis. Throughout the day thousands of protesters carried red flags, honked their horns and tied red ribbons on their vehicles as they moved peacefully in several large convoys through Bangkok. The organisers made speeches and music performance to supporters through social media platforms to maintain a degree of social distancing throughout the protests. Many Bangkok"s residents came out to greet the convoys, many cheering them on and making gestures of support. "Our goal is to drive Prayuth out of the position of prime minister and we will do this peacefully," Nattawut said earlier during the vehicle rally. Police defended their use of force during the clashes, saying it was sometimes necessary to maintain public order. They added that they had complied with international standards in using teargas, rubber bullets and water cannon. "We need to maintain the law and keep the peace," Thai police chief Suwat Jangyodsuk told reporters, without specifying whether the police intend to use force. More than 130 people have been arrested in the latest round of anti-government protests since mid-July, Suwat said.