SEOUL: US President Barack Obama's top envoy for the Democratic People's Republic of Korea (DPRK) warned of "consequences" if it pushes ahead with a threatened atomic test and urged Pyongyang to instead return to dialogue with Washington to defuse nuclear tensions.

Stephen Bosworth arrived in Seoul from Beijing just hours after the DPRK accused the Obama administration of harboring a hostile policy toward Pyongyang, saying it would expand its nuclear arsenal in response.

"Nothing would be expected from the US, which remains unchanged in its hostility toward its dialogue partner," the DPRK's Foreign Ministry said in a statement carried on Friday by state media. The DPRK "will bolster its nuclear deterrent as it has already clarified."