Shinzo Abe was elected Japan's prime minister by the lower house of parliament on Wednesday after he swept to power on a hawkish platform of getting tough on diplomatic issues while fixing the economy.

Abe, who was prime minister from 2006 to 2007, unveiled his new cabinet within hours of his election, as he rushes to draft an extra budget to spur the flagging economy.

Taro Aso, another former prime minister in Japan's revolving-door political system, was tapped as both Abe's deputy and also finance minister.

Earlier Wednesday, the yen tumbled against the dollar on growing speculation that the Bank of Japan will usher in further easing measures -- a key plank of Abe's campaign.

Abe, 58, achieved a resounding election victory earlier this month for his Liberal Democratic Party over the Democratic Party of Japan (DPJ).

On Wednesday he secured 328 votes to 57 for the DPJ's new leader Banri Kaieda, the industry minister during last year's Fukushima nuclear crisis.

Abe, Japan's seventh premier in less than seven years, replaces Yoshihiko Noda whose DPJ suffered a stinging defeat at the polls.

The party, which came to power in 2009, was seen as being punished for policy flip-flops and its clumsy handling of the atomic disaster.

The foreign minister job in the new cabinet went to Fumio Kishida, who was a state minister in charge of Okinawan affairs during Abe's previous tenure.

The appointment was seen as a reflection of Abe's desire for progress on the relocation of US military bases in the southern island chain, and comes as Japan is embroiled in a territorial row with China.

The defence portfolio went to Itsunori Onodera, who served as deputy foreign minister for a year during Abe's earlier premiership and during that of his successor Yasuo Fukuda.

Sadakazu Tanigaki, the head of the LDP when the party was in opposition after ruling Japan for most of the past six decades, became justice minister.

Abe has vowed to pressure the central bank for further easing measures to boost growth, while also promising big government spending to spur the economy.

He won conservative support with nationalistic pronouncements on diplomacy amid the row with Beijing over a group of East China Sea islands, saying Japan would stand firm on its claim to the chain.

He has also said he would consider revising Japan's post-war pacifist constitution, alarming officials in China and South Korea.

But Abe quickly toned down the campaign rhetoric and has said he wants improved ties with China, Japan's biggest trading partner. He called for a solution through what he described as "patient exchanges".

China called on Abe to meet it "halfway" to try and improve relations that have been hurt by the debilitating territorial dispute.

"We hope the new Japanese administration will meet the Chinese side halfway and make concrete efforts to overcome difficulties in bilateral relations," foreign ministry spokeswoman Hua Chunying told reporters.

South Korea has its own islands dispute with Japan. But President Lee Myung-Bak sent Abe his congratulations, saying the countries have engaged in "close cooperation and exchanges as close neighbours and friendly nations".

Analysts said Abe was likely to delay drastic policy measures ahead of upper house elections next year, while the LDP's moderate junior coalition partner New Komeito could also balance his right-leaning instincts.