North Korea on Thursday shelled a South Korean military unit on the western section of the inter-Korean border, the South’s Yonhap news agency said, citing military sources.

The Defence Ministry said it could not immediately confirm the report, which comes at a time of elevated cross-border tensions, following a landmine attack earlier this month that Seoul blamed on Pyongyang.

But the action triggered a retaliatory shooting by South Korea.

South Korea also fired dozens of shells across the border into North Korea in retaliation for an apparent North Korean rocket attack, Seoul’s defence ministry said.

“Our side staged a counter-attack with dozens of 155mm shells,” a ministry spokesman told AFP.