Seoul - North and South Korea on Wednesday strengthened the monitoring of their border in the Yellow Sea, a day after engaging in a sea battle there, the South Korean government said. South Korea's naval forces were put on heightened alert "in preparation for additional provocations by the North," South Korean Navy Chief of Staff Jung Ok Keun said in Seoul, according to the national news agency Yonhap.
A spokesman for the South's Joint Chiefs of Staff said North Korea's navy had also stepped up its watch over the border off the neighbours' west coasts.
He said there have been no other unusual incidents since Tuesday's clash, in which North and South Korean vessels exchanged fire, leaving a North Korean patrol boat heavily damaged and in flames, according to the South Korean military.
President Lee Myung Bak was quoted as expressing concerns at a security meeting Tuesday in Seoul of potential retaliation from Pyongyang.
Tuesday's clash lasted about two minutes. The South said a North Korean patrol boat crossed the Northern Limit Line, the countries' disputed maritime border in the Yellow Sea. South Korean ships fired warning shots, and the patrol boat began firing directly at the South's vessels, it said.
North Korea's military charged the South Korean ships with violating the North's territorial waters by chasing the patrol boat over their border. Pyongyang accused Seoul of a "grave provocation" and demanded an apology.
The sea battle was the first between the two Koreas in seven years.
