North Korea fired off three short-range rockets into the East Sea on Thursday, South Korea's Joint Chiefs of Staff (JCS) said, minutes before Pope Francis landed here with a message of peace for the Korean Peninsula.

The projectiles, presumed to have come from a 300-millimeter multiple rocket launcher, "were fired from its eastern border town of Wonsan in a northeastern direction for about 25 minutes from 9:30 a.m. in succession," JCS spokesman Um Hyo-sik told reporters.

They were presumed to have landed in the East Sea after flying some 220 kilometers, he said, noting that Pyongyang did not impose a no-fly, no-sail zone ahead of the launch.

"Our military has maintained vigilance against additional launches and is taking necessary steps," Um added.

Military sources here have said the communist country seems to be test-firing the rockets in an effort to increase their range. Though the launcher, called the KN-09, was thought to have a range of 160 kilometers, rockets fired last month traveled 210 kilometers. (Yonhap)