SEOUL, Aug 15 (Reuters) - South Korean police mobilised hundreds of buses and set up dozens of checkpoints on Sunday to head off political rallies in Seoul, as some groups pushed ahead with annual protests in defiance of warnings over the spread of the novel coronavirus. South Korea has largely been held up as a coronavirus success story, but is grappling with a fourth wave of infection that took new daily cases above 2,200 last week for the first time, partly fuelled by the more transmissible Delta variant. read more The government has banned protests and vowed punishment for any legal violation ahead of Sunday"s Liberation Day, mindful of virus outbreaks from an anti-government rally and church gathering last August which resulted in over 1,800 cases. Police parked busses along main avenues and around a large square in downtown Seoul to seal them off, and set up more than 80 checkpoints to block vehicles carrying demonstrators and equipment. Subway trains and public buses did not stop at stations around potential protest venues. But footage from local TV networks showed several groups still encouraging demonstrations by individuals and marches where participants maintain distance from each other, to protest issues as varied as government policy and worker rights. On Saturday, police disbanded an organisation that hosted last August"s rally. A court also issued an arrest warrant for the leader of a major labour union for arranging multiple illegal protests since May. The church that was at the centre of an outbreak last August also held an in-person service attended by some 800 people on Sunday in breach of distancing curbs, the Yonhap news agency reported, citing district officials. Reuters could not immediately reach the church or district authority for comment. "Despite the government"s repeated warnings, some groups pressed ahead with illegal protests," Prime Minister Kim Boo-kyum told an intra-agency meeting, pledging "zero tolerance" measures. "You have to remember how many people suffered from last year"s rally." The Korea Disease Control and Prevention Agency (KDCA) reported 1,817 new virus cases for Saturday, the highest recorded on any Saturday since the pandemic began last year. Total infection cases rose to 223,928, with 2,156 deaths. The fourth wave came as South Korea struggles to kickstart its inoculation drive amid vaccine shortage and shipment delays, though it has secured 193 million doses for its 52 million population. read more Only 19% of South Koreans have been fully vaccinated as of Saturday, KDCA data showed, but President Moon Jae-in, in his Liberation Day speech on Sunday, vowed to boost that number to 70% by October, without detailing how. About 43.6% of the population have received at least one dose of vaccine. The government"s previous target was to reach 70% by September.