Japan's ruling coalition has lost its majority in the country's upper house, but Prime Minister Shigeru Ishiba has said he has no plans to quit, BBC reported.

Voters went to the polls on Sunday for the tightly-contested election, being held at a time of frustration at the coalition of the Liberal Democratic Party (LDP) and its junior partner Komeito over rising prices and the threat of US tariffs.

Speaking after polls closed on Sunday, the prime minister said he "solemnly" accepts the "harsh result" but that his focus was on trade negotiations.

Having already lost its majority in Japan's more powerful lower house last year, the defeat will undermine the coalition's influence, according to BBC.