Aust united with S Korea over nuke threat

Julie Bishop has pledged solidarity with South Korea in the face of the North's ongoing nuclear threat.

The foreign minister and Defence Minister Marise Payne are in Seoul for talks with their South Korean counterparts.

"We stand united with (South Korea) against the provocative and threatening behaviour of North Korea," Ms Bishop told reporters.

The ministers discussed ways to work together to compel North Korea back to the negotiating table.

The visit comes as a small quake was detected near the North's nuclear test site early on Friday.

The tremor was the latest in a string of at least three shocks to be observed since Pyongyang's September 3 nuclear test, which caused a 6.3 magnitude earthquake.

Friday's quake was a magnitude 2.7 with a depth of 3km in North Hamgyong Province in North Korea, the Korea Meteorological Administration said.

The series of quakes has prompted experts and observers to suspect the last test, which the North claimed to be of a hydrogen bomb, might have damaged the mountainous location in the northwest tip of the country, where North Korea's six nuclear tests were conducted.

Senator Payne and Ms Bishop have also visited the Korean War Memorial to pay their respect to the 340 Australians who lost their lives during the Korean War.