The South Korean government said a malicious code from unknown cybercriminals caused computer networks tied to several television stations and banks to fail Wednesday.
North Korea was suspected by its southern rival of targeting its computer infrastructure in the past years. An unnamed South Korean presidential official said it wasn't yet clear if North Korea was behind the latest incident, South Korean news agency Yonhap reports.
The Korean Central News Agency reported last week that North Korea's adversaries were mounting cyberattacks on the country at the same time joint South Korean-U.S. military exercises began in the region.
Yonhap reported that access to the Internet in North Korea was blocked for about 24 hours starting March 13. The attack allegedly targeted state-run news outlets.
North Korea recently pulled out of the armistice agreement that halted the Korean War in the 1950s in response to international pressure.
The U.N. Security Council last week censured North Korea for its February underground nuclear test, which the North Korean government said was part its campaign against the United States.