SEOUL (AFP) - North Korea's leader Kim Jong Un inspected a set of newly built warships and issued orders to bolster the navy, state media said on Saturday.

The visit followed a two-day joint naval drill near the Korean peninsula involving a US nuclear aircraft carrier which sparked a series of angry responses and threats from Pyongyang.

On Friday the North slammed a naval drill by US, South Korean and Japanese warships as a "serious military provocation" and vowed to "bury in the sea" the American carrier taking part in the exercise.

Accompanied by the Chief of the Korean People's Army General Staff Ri Yong Gil and navy commander Kim Myong Sik, Mr Kim inspected the newly built warships and "guided their maneuvers", the North's Korean Central News Agency (KCNA) said.

KCNA gave no further details about the number or type of the newly built warships.

Mr Kim praised the scientists, technicians and workers for building the modern warships - which were described by KCNA as "on a high level of intelligence and light in weight" - in a short time-span.

He was "greatly satisfied" to watch "the high maneuverability and striking capability" of the vessels.

The North Korean leader vowed to bolster up his naval force and steadily increase his nation's naval combat capability, the report added.