SEOUL - North Korea has maintained readiness to conduct a new nuclear test at any time, a South Korean military official said on Friday.Surveillance assets of the South Korean and US militaries are closely monitoring the North's Punggye-ri nuclear test site on its east coast, the official who declined to be identified said by telephone. He declined to comment whether there were fresh signs pointing to an imminent test.US Fox News reported on Thursday local time that the North is in the final stages of preparing for another nuclear test which could come in the next few days, citing US officials with knowledge of recent intelligence.