SEOUL (Reuters) - North Korea's long-range rocket launched on Sunday may have failed, South Korea's Yonhap news agency said.

Earlier, South Korean media had reported that the rocket appeared to have successfully separated the first and second stage boosters with the first stage falling into the sea off the west coast of the Korean peninsula.

North Korea, which claims its rocket program is aimed at launching satellites, launched the rocket from its missile base on the west coast on Sunday in defiance of U.N. sanctions barring it from using ballistic missile technology.

(Reporting by Jack Kim and Ju-min Park; Editing by Mark Bendeich)