Seoul  - South Korea wants to discuss the possibility of developing more powerful ballistic missiles with the US as a deterrent against North Korea, the national news agency Yonhap reported on Tuesday.

"I believe the issue can be discussed by working-level officials of the United States and South Korea," South Korean Defence Ministry spokesman Won Tae-jae told the media in Seoul.

South Korea previously agreed not to build missiles with a range of over 300 kilometres capable of carrying warheads of more than 500 kilograms.

Major General Frank Panter, assistant chief of staff of US Forces Korea, last week told aides to South Korean legislators that the US would consider allowing the range to be extended.

North Korea's rocket and nuclear tests have prompted politicians in South Korea to call for the development of more powerful rockets.

On Saturday North Korea fired seven rockets over the Sea of Japan.(dpa)