Japan's ruling coalition has lost its majority after snap elections, Japanese media projected early on Monday, in what would be a major blow to new Prime Minister Shigeru Ishiba.

Ishiba, 67, called Sunday's election only days after taking office on October 1, aiming to bolster his position and that of his scandal-hit Liberal Democratic Party (LDP), which has governed Japan almost continuously for seven decades.

But national broadcaster NHK and other media outlets reported in the hours after polls closed that the LDP – in the party's worst result since 2009 – together with its long-term junior coalition partner Komeito had fallen short of the 233 seats needed for a majority in Japan's lower house.

Voters in the world's fourth-largest economy have been rankled by rising prices and the fallout from a party slush fund scandal that helped sink previous premier Fumio Kishida.

The LDP remains the top party in Japan's parliament, and a change of government is not expected. But the results create political uncertainty.

Falling short of a majority makes it difficult for Ishiba to get his party’s policies through parliament, and he may need to find a third coalition partner.

The LDP’s coalition retains a majority in the less powerful upper house. Public broadcaster NHK reported that the ruling coalition with junior partner Komeito secured 215 seats, down sharply from the majority of 279 it previously held.

"We are receiving severe judgement," Ishiba told NHK earlier on Sunday while it was still unclear whether the coalition would secure enough seats.

Voters "expressed their strong desire for the LDP to do some reflection and become a party that will act in line with the people's will," he said.

Footage from the LDP headquarters showed gloomy faces as projections based on exit polls indicated Ishiba's justice and agriculture ministers were likely to lose their seats.

The Constitutional Democratic Party of Japan, led by centrist leader Yoshihiko Noda, made huge gains to 148 seats, from its previous 98.

“We accomplished our goal of preventing the ruling coalition from a majority, which was a major achievement,” Noda said.

Noda called the election a rare chance for a change of government, and said he seeks to lead a coalition with other opposition groups to do so. But his party has had trouble finding partners, and some voters were skeptical about the opposition’s ability and inexperience.

For Ishiba, potential additional partners include the Democratic Party of the People, which calls for lower taxes, and the conservative Japan Innovation Party.

DPP head Yuichiro Tamaki said he was open to “a partial alliance.” Innovation Party chief Nobuyuki Baba has denied any intention to cooperate. As of early Monday, DPP had 28 seats and the Innovation Party 38.

Experts say a CDPJ-led government is not in the picture because of its lack of viable policies.

“If they take power and try to change the economic and diplomatic policies of the current government, they will only end up collapsing right away,” said Izuru Makihara, a University of Tokyo professor of politics and public policy.

“Realistically, Ishiba's ruling coalition would seek a partnership with either the Innovation Party or the Democratic Party of the People”, he said. (Agencies)