Japanese PM claims backing for policies after party wins Tokyo elections Shinzo Abe's Liberal Democratic party and coalition partner win majority in capital's assembly weeks before national elections

Japan's prime minister, Shinzo Abe, has claimed popular backing for his economic polices after his Liberal Democratic party (LDP) swept to an easy victory in Tokyo's assembly elections on Sunday, just weeks before crucial national elections.

The LDP became the biggest single party in the 127-seat Tokyo metropolitan assembly, with 59 seats, up from 39 before the vote. Its coalition partner, the Buddhist-backed New Komeito, won 23 seats, giving the parties a comfortable majority.

The election saw the continued decline of the left-of-centre Democratic party of Japan (DPJ) – which led the national government just a year ago – and a surprise resurgence by the Japan Communist party, which drew support from voters who have yet to feel the benefits of "Abenomics" – Abe's programme of massive public investment, monetary easing and structural reforms.

"We have received a good evaluation of our handling of the government over the past six months," Abe told reporters. "We would like to do our very best so people can feel that the economy is recovering as soon as possible."

Yoshihide Suga, the chief cabinet secretary, said the result "could not have been better", describing it as "a blessing from Tokyo's voters to the Abe government". The win was the LDP's biggest in the capital since 2001, when it was led by the popular reformer Junichiro Koizumi.

The result has given Abe added momentum as the LDP prepares for upper house elections on 21 July. Victory in that election would give the party control of both houses of Japan's parliament, the National Diet, ending the political stalemate and giving Abe free rein to press on with his political agenda.

Abe, a defence hawk, wants to revise Japan's constitution to allow its forces to play a more active role overseas, including coming to the aid of the US and other allies under attack. He has also hinted at reassessing Japan's "masochistic" view of its conduct during the war, a move that would raise tensions with China and South Korea.

The rightwing Japan Restoration party, a potential ally in Abe's push for constitutional reform, lost one of its three seats in the assembly and is expected to struggle in next month's upper house elections.

The Restoration party's co-leader, Toru Hashimoto, recently sparked a diplomatic storm after claiming that tens of thousands of Asian womenforced to work as sex slaves in Japanese military brothels before and during the second world war had been "necessary" to main discipline among troops. Hashimoto has indicated he will resign if his party performs badly next month.

The Communists were the chief beneficiaries of a near-record low turnout of 43.5% and the absence of a viable mainstream alternative to Abe's LDP.

"This tells us that the LDP is likely to win the upper house primarily because the opposition is divided and there is no alternative," Steven Reed, a political science professor at Chuo University in Tokyo, told Associated Press.

The Communist party more than doubled its strength in the Tokyo assembly to 17 seats, making it the third-largest party.

"We are very happy because voters supported us on the issues we campaigned on," Kazuo Shii, the party's chairman, told reporters. "It is important to take on the LDP and offer an alternative."

The election was a disaster for the DPJ, which won the 2009 general election by a landslide on promises to support families and the low-paid, and steer Japan's foreign policy away from reliance on the US.

The party, the biggest in the assembly before Sunday with 43 seats, slumped to 15 seats. "It's a tough outcome for us, and we humbly accept it," the DPJ's former leader, Katsuya Okada, told reporters.