PYONGYANG, Nov. 24 (Xinhuanet) -- Several South Korean warships on Monday fired shots at a patrol boat of the Democratic People's Republic of Korea (DPRK) which was on a regular patrol northwest of Baekryeong Island in the Yellow Sea, the DPRK's official Korean Central News Agency reported, quoting military sources.

　　The DPRK regarded the incident as a serious armed provocation and warned the South Korean military of possible grave consequences caused by the act, said the report.

　　However, the South Korean side said a DPRK patrol boat briefly crossed a controversial inter-Korean border near South Korean Baekryeong Island in the Yellow Sea on Monday.

　　"A DPRK patrol ship violated the North Limit Line (NLL) about 0.4 miles northwest of Baekryeong Island at 1:36 p.m. (0436 GMT)," South Korean Yonhap News Agency quoted an official at the Joint Chiefs of Staff (JCS) of South Korea as saying.

　　"The vessel moved 0.4 mile into southern waters, but returned to the northern side four minutes later after the South Korean Navy's 150-ton, high-speed ship fired five warning shots," he added.

　　The JCS said it detected no particular movements from the DPRK navy during the violation.

　　South Korea and the DPRK differ on the NLL, which was accepted by Seoul as inter-Korean border, while Pyongyang denied the conception. Armed conflicts involving the countries' warships took place near the disputed waters in 1999 and 2002.