North Korea yesterday test-fired 18 rockets into the sea, South Korea's defence ministry said.
It is the latest in a series of launches that have provoked criticism from Seoul and Washington.
The rockets were fired off the North's east coast and flew about 70km over the Sea of Japan (East Sea), a ministry spokesman said.
The 10 rockets were fired at 5.20pm (Singapore time) and eight more at 7.03pm (Singapore time).
Seoul's military "has maintained a close watch for possible North Korean provocations", AFP reported the spokesman as saying.
Yonhap news agency earlier reported that 10 short-range missiles were fired.
South Korean troops have increased vigilance following a series of rocket or missile launches in late February and this month.
The activity coincides with annual South Korean-US military exercises that started last month and will run until mid-next month.
Get The New Paper for more stories.