The Democratic People's Republic of Korea (DPRK) fired artillery Wednesday again toward waters north of the disputed maritime border in the Yellow Sea, only hours after the first firing, Seoul's Yonhap News Agency reported quoting an unnamed government source.

The DPRK started firing scores of artillery around 3:25 p.m. local time (0625GMT) shells into waters near the contentious sea border called Northern Limit Line (NLL) off the west coast of the Korean peninsula, within the range of no-sail zones designated by the DPRK a day ago, according to Yonhap.

South Korean military only sent two warning messages without firing warning shots in response to the latest shootings, Yonhap said.

South Korean military authorities have not confirmed the report.

Earlier Wednesday, the DPRK fired some 30 artillery shells for more than an hour starting 9:05 a.m.(0005GMT) local time, which fell into waters north of the disputed sea border called Northern Limit Line (NLL), within the range of no-sail zones designated by the DPRK a day ago.

South Korean military responded immediately by firing some 100 Vulcan cannons as warning shots, but there have been no casualties or injuries reported as the two sides fired into the air and not at each other.

The firings follow the DPRK's recent designation of two no-sail zones in waters near the NLL, fixed unilaterally by the U.S.-led United Nations Command after the 1950-1953 Korean War, where the latest naval skirmish between South Korea and the DPRK took place in November last year.