South Korean President Park Geun Hye vowed on Wednesday (Jan 13) to make all diplomatic efforts to impose the strongest-ever sanctions against North Korea as punishment for its latest nuclear test.

She also urged the international community, including China, to adopt a tougher line against North Korea and come up with punitive action that is different from previous ones and powerful enough to make Pyongyang change its course.

North Korea's nuclear test is not only a "grave provocation and serious threat" to South Korea, but also an unacceptable challenge to peace and security in North-east Asia and the world, said Ms Park during her televised annual national address on Wednesday morning.

Last week's nuclear test was North Korea's fourth since 2006, and the second conducted under third-generation leader Kim Jong Un. The reclusive state is also subject to UN sanctions for its three previous nuclear tests since 2006.

South Korea will continue to work with the UN, as well as its allies United States and Japan, on countermeasures against North Korea, said Ms Park.

The nuclear negotiators from the three countries are slated to meet in Seoul on Wednesday for talks.

The President also vowed to continue blasting propaganda K-pop songs through loudspeakers installed along the border which apparently have been an effective form of psychological warfare against North Korea.

Pyongyang has responded with its own loudspeaker broadcast, glorifying Mr Kim while criticising Ms Park.

In her address, Ms Park also called for support for a pending anti-terror Bill, which will help protect the country against security threats from international terror groups as well as North Korea.

She also stressed the urgency for labour reforms, part of efforts to revitalise the country's flagging economy, to be passed.