Tokyo (CNN) Landslides and flooding caused by torrential rain in Japan have killed 200 people in what has become one of the deadliest natural disasters to hit the country since the earthquake and tsunami of 2011.

Around 21 people are unaccounted for since the downpour that began late last week, Japanese Chief Cabinet Secretary Yoshihide Suga said Thursday.

"The government will push for the swift delivery of support to the disaster victims," Suga said. "We are tackling this with utmost effort."

Some 75,000 responders have been deployed to the area for search and rescue operations. Suga warned that thunderstorms and landslides in the coming hours could pose further danger.

Japanese Prime Minister Shinzo Abe was in Okayama Prefecture Wednesday morning surveying the damage in one of the hardest-hit areas. He canceled a scheduled trip to Europe and the Mideast to focus on disaster relief efforts.

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