North Korea twice fired shells near the flashpoint Yellow Sea border with South Korea yesterday, prompting warning shots from the South’s marines in response, Seoul’s military said.

The incidents fuelled already high tensions along the disputed sea border, which saw bloody naval skirmishes in recent years and a deadly shelling attack on South Korea’s Yeonpyeong island last November.

The first incident came at 1 p.m. (0400 GMT), when Seoul’s defence ministry said a North Korean shell landed near the border, known as the Northern Limit Line (NLL).

Marines based on Yeonpyeong island broadcast a warning and then fired three warning shots from K-9 self-propelled guns.

The North’s coastal artillery fired again at 7.46 p.m. towards the border and the South again fired warning shots in response, a ministry spokesman said.

“North Korea fired two shots and one shell landed near the NLL. Our side fired three shots from the K-9,” he said. “There were no more shots afterwards but we’re now closely watching the situation.”

The ministry said the initial shells may have been fired during a training exercise.