The loss on Sunday left the Liberal Democrats a minority party in both houses of Parliament, while two new nationalist parties surged.

The fringe far-right Sanseito party emerged as one of the biggest winners in Japan's upper house election, gaining support with warnings of a "silent invasion" of immigrants, and pledges for tax cuts and welfare spending.

Exit polls suggest Prime Minister Shigeru Ishiba's coalition is likely to lose a majority its majority in the smaller of Japan’s two parliamentary houses in a key election.