The organisers of the PyeongChang Winter Olympics said Saturday its servers were hacked by an unidentified attacker during the opening ceremony the previous day.The PyeongChang Organising Committee for the 2018 Olympic & Paralympic Games (POCOG) said it experienced a cyber attack which caused a malfunction of the Internet protocol televisions (IPTVs) at the Main Press Centre, reports Yonhap news agency.The organisers accordingly shut down the servers to prevent further damage, leading to the closure of the PyeongChang 2018 website.Due to the shutdown of the website, spectators who purchased tickets to 2018 Winter Games events were unable to print their reservations.The website was only normalised on Saturday morning even as the details of where the attack originated remain unknown, the organisers said.Security experts have warned that major international events such as the Olympics are major targets for hackers.In an official statement, POCOG said there were some issues late Friday that impacted "non-critical systems" for few hours and added that they had no effect "on the safety and security of any athletes or spectators" during the opening ceremony."We are currently investigating the cause and will share further information as we have more details," Sung Baik-you, POCOG spokesperson, said.