Seoul – North Korea on Thursday fired artillery shells near its disputed maritime border with South Korea for a second day, news reports from Seoul said. The North began firing towards the South Korean island of Yeonpyeong near the Northern Limit Line (NLL) in the Yellow Sea at 8:15am (23:15 GMT Wednesday), the Yonhap News Agency said, quoting a defence official. The shots fell into the sea short of the disputed maritime border, Yonhap added. Seoul would not return fire as long as nothing was fired over the border, a military spokesman said. Pyongyang said its shots were part of an annual military exercise. Seoul stressed that its response Wednesday had consisted only of warning shots. The incidents come at a time of a renewed rise in tensions between the two Koreas after the North this month threatened a 'holy war' against its southern neighbour. North Korea on Monday declared parts of the disputed area in the Yellow Sea 'no-sail' zones, raising speculation that Pyongyang was preparing missile tests. Analysts said they believed Pyongyang's provocative gesture intends to increase pressure on Washington and Seoul to respond positively to a Pyongyang proposal to start talks on a peace treaty.