South Korea said on Wednesday it suspected North Korea of attempting cyberattacks against targets in the South, following a nuclear test by the North this month that defied United Nations sanctions.

South Korea has been on heightened military and cyberalert since the Jan. 6 test, which Pyongyang called a successful hydrogen bomb test, although U.S. officials and experts doubt that it managed such a technological advance.

"At this point, we suspect it is an act by North Korea," Jeong Joon-hee, a spokesman of the South's Unification Ministry, told a news briefing, when asked about reports that the North might have attempted cyberattacks.