Some North Korean troops stationed along the border have donned a camouflage uniform similar to that worn by South Koreans, apparently to practise intrusion drills, a defence ministry official said on Tuesday.
The move prompted the South to advance the supply of new uniforms for its own troops to avoid confusion, the official told journalists in a background briefing.
"It's been confirmed some North Korean frontline troops are wearing uniforms with woodland camouflage pattern which is similar to those of South Korean uniforms," the official said.
"Our judgment is that the North's special forces stationed there are staging intrusion drills wearing the uniforms."
The South's military has begun supplying new "digital camouflage" uniforms and is considering speeding up the distribution following the North's move.
The North is believed to have some 200,000 special forces and to have deployed some 50,000 of them along the border with the South, the ministry said.
Tensions are high following the North's shelling last month of a South Korean border island, which killed four people including civilians.
The South's forces are on alert for any fresh attacks.