SEOUL: North Korean hackers may have infected up to 20,000 South Korean smart- phones with malicious software, South Korea's National Intelligence Service (NIS) was reported as saying yesterday. The malware, disguised as games, was spread on South Korean websites between May and September this year, according to Yonhap News Agency. The NIS said it had worked with the websites owners and the government to remove the applications and block relevant hacking channels. It didn't specify what the suspected malware was intended to do. Pyongyang was reported earlier this year to have doubled its network of hackers inside the country and abroad to number nearly 6,000 people, Yonhap said. North Korea has denied any involve- ment and accuses Seoul of fabricat- ing the incidents to fan cross-border tensions. AGENCIES