* Abe promises aggressive monetary, fiscal policies
* Yen hits 20-month low on "Abenomics" expectations
* Abe appoints many right-leaning allies to cabinet
New Japanese Prime Minister Shinzo Abe vowed on Wednesday to battle deflation and a strong yen, and bolster ties with the United States as he kicked off a second administration committed to reviving the economy while coping with a rising China.
A hawk on security matters, Abe, 58, has promised aggressive monetary easing by the Bank of Japan and big fiscal spending by the debt-laden government to slay deflation and weaken the yen to make Japanese exports more competitive.
Critics worry, however, that he will pay too little heed to reforms needed to generate growth despite an ageing, shrinking population and reform a creaking social welfare system.
The grandson of a former prime minister, Abe has staged a stunning comeback five years after abruptly resigning as premier in the wake of a one-year term troubled partly by scandals in his cabinet and public outrage over lost pension records.
"With the strength of my entire cabinet, I will implement bold monetary policy, flexible fiscal policy and a growth strategy that encourages private investment, and with these three policy pillars, achieve results," Abe told a news conference after parliament voted him in as Japan's seventh prime minister in six years.
Abe's long-dominant Liberal Democratic Party (LDP) surged back to power in this month's election, three years after a crushing defeat at the hands of the novice Democratic Party of Japan.
CLOSE ALLIES, PARTY RIVALS
Abe appointed a cabinet of close allies who share his conservative views in key posts, but leavened the line-up with LDP rivals to provide ballast and fend off criticism of cronyism that dogged his first administration.
Former prime minister Taro Aso, 72, was named finance minister and also received the financial services portfolio.
Ex-trade and industry minister Akira Amari becomes minister for economic revival, heading a new panel tasked with coming up with growth strategies such as deregulation.
Policy veteran Toshimitsu Motegi, as trade minister, will be tasked with formulating energy policy in the aftermath of the Fukushima nuclear disaster last year.
Loyal Abe backer Yoshihide Suga was appointed chief cabinet secretary, a key post combining the job of top government spokesman with responsibility for coordinating among ministries.
Others who share Abe's agenda to revise the pacifist constitution and rewrite Japan's wartime history with a less apologetic tone were also given posts, including conservative lawmaker Hakubun Shimomura as education minister.
"These are really LDP right-wingers and close friends of Abe," said Sophia University professor Koichi Nakano. "It really doesn't look very fresh at all."
Fiscal hawk Sadakazu Tanigaki, whom Abe replaced as LDP leader in September, becomes justice minister while two rivals who ran unsuccessfully in that party race - Yoshimasa Hayashi and Nobuteru Ishihara - got the agriculture and environment/nuclear crisis portfolios respectively.
CENTRAL BANK THREATENED
Business leaders welcomed the new cabinet, but the biggest corporate lobby, Keidanren, urged the government to take part in the U.S.-led Trans-Pacific Partnership (TPP) trade pact, Kyodo news agency said. The LDP has been wary of the pact given the political clout of the heavily protected farm sector.
The yen has weakened about 9.8 percent against the dollar since Abe was elected LDP leader in September. On Wednesday, it hit a 20-month low of 85.38 yen against the greenback on expectations of aggressive monetary policy easing.
Abe has threatened to revise a law guaranteeing the Bank of Japan's (BOJ) independence if it refuses to set a 2 percent inflation target.
BOJ minutes released on Wednesday showed the central bank was already pondering policy options in November, concerned about looming risks to the economy. The BOJ stood pat at its November rate review meeting, but eased this month in response to intensifying pressure from Abe.
Abe also promised during the election campaign to take a tough stance in territorial rows with China and South Korea over separate chains of tiny islands, while placing priority on strengthening Japan's alliance with the United States.
On Wednesday, he repeated his resolve to firm up ties with Washington and his intention to protect "the people's lives, Japanese territory and its beautiful oceans".
China expressed hope that Abe's cabinet would work with Beijing to improve ties, but reiterated that the disputed isles were its territory. "We hope Japan works with China with sincerity and makes real efforts to solve relevant problems through dialogue and negotiations," Chinese Foreign Ministry spokesman Hua Chunying told a news conference in Beijing.
Abe named low-profile lawmakers to the foreign and defence portfolios. Itsunori Onodera, 52, who was senior vice foreign minister in Abe's first cabinet, becomes defence minister while Fumio Kishida, 55, a former state minister for issues related to Okinawa island - host to the bulk of U.S. forces in Japan - was appointed to the top diplomatic post. Unlike many others in the cabinet, Kishida has an image as something of a diplomatic dove.
Abe, who hails from a wealthy political family, made his first overseas visit to China to repair chilly ties when he took office in 2006, but has said his first trip this time will be to the United States.
He may, however, put contentious issues that could upset key trade partner China and fellow-U.S. ally South Korea on the backburner to concentrate on boosting the economy, now in its fourth recession since 2000, ahead of an election for parliament's upper house in July.
The LDP and its small ally, the New Komeito party, won a two-thirds majority in the 480-seat lower house in the Dec. 16 election. That allows the lower house to enact bills rejected by the upper house, where the LDP-led block lacks a majority.
But the process is cumbersome, so the LDP is keen to win a majority in the upper house to end the parliamentary deadlock that has plagued successive governments since 2007.
"Trust in our party has not yet been fully restored and I feel we are still viewed with critically by the people, so I want to get results as soon as possible to restore trust," Abe told the news conference.