Japan said on Wednesday it is investigating the possible involvement of a pro-Russian group after multiple government websites suffered disruptions a day earlier.
The pro-Russian group "Killnet" was quoted by media as saying it was responsible for attacks on the government websites.
Japan's government is looking into whether problems with accessing more than 20 websites across four government ministries was caused by a denial-of-service (DDoS) attack, Chief Cabinet Secretary Hirokazu Matsuno told reporters.
In a DDoS attack hackers attempt to flood a network with unusually high volumes of data traffic in order to paralyse it.
"We are aware that the (Killnet) hacker group suggested it was behind the attacks, but at the moment we are still investigating the cause of the failures, including the group's involvement," he said.
The government websites could not be accessed on Tuesday evening but services were restored on the same day, Matsuno added.
Japan's digital agency later said in a tweet that its e-Gov administrative portal was experiencing log-in problems to some services on Wednesday, without specifying the cause. The portal had been among those targeted on Tuesday, according to public broadcaster NHK.
(Reporting by Tim Kelly, Sakura Murakami and Chang-Ran Kim; Editing by Shri Navaratnam and Edwina Gibbs)
