North Korea held a live-fire drill near its maritime border with South Korea on Tuesday, with Seoul vowing a "strong" response if any shells fall on its side of the disputed boundary.

North Korea held a live-fire drill near its maritime border with South Korea on Tuesday, with Seoul vowing a "strong" response if any shells fall on its side of the disputed boundary.

A similar exercise a month ago resulted in the two rivals firing hundreds of artillery shells into each other's territorial waters.

North Korea had given advance notice of the drill which began around 2:00 pm (0500 GMT), the South Korean defense ministry said.

"Our military is fully prepared," ministry spokesman Kim Min-Seok said.
"If any shell lands on our side of the border, South Korea will respond strongly."

The Yonhap news agency reported that South Korean jet fighters had been scrambled to patrol the border area.

Fishing vessels had been warned off and local officials on the border islands of Yeonpyeong and Baengnyeong said residents were advised to leave their homes.

The de-facto maritime boundary between the two Koreas -- the Northern Limit Line -- is not recognized by Pyongyang, which argues it was unilaterally drawn by the US-led United Nations forces after the 1950-53 Korean War.

Both sides complain of frequent incursions by the other and there were limited naval clashes in 1999, 2002 and 2009.