South Korean Prime Minister Chung Hong-won visited Thursday a front-line island near the tense western sea border with the Democratic People's Republic of Korea (DPRK) amid heightened military tensions following DPRK's nuclear test last month, local media reported.

The prime minister paid respect to the two soldiers killed in the DPRK's 2010 artillery attack on the island of Yeonpyeong, and visited a military unit stationed there.

"As a strong buttress protecting the lives and property of the people, I ask for your full preparations such as maintaining a high alert to properly respond to any types of North Korean (DPRK) provocations," Chung told the soldiers, according to Yonhap News Agency.

His visit came after top DPRK leader Kim Jong Un guided live ammunition exercises that many believe were targeted at South Korean border islands.

Cross-border tensions remain high as South Korea and the United States, which together pushed for new sanctions condemning the DPRK's nuclear test, are engaged in joint drills the DPRK call a pretext for invasion.

The 2010 shelling also killed two South Korean civilians.