TOKYO: Former TV anchorwoman Yuriko Koike signalled Monday she would run to be Japan's first female prime minister, as a buoyant opposition vowed to cut short the tenure of any new leader.

Koike, 56, said she had enough backers to contest the September 22 vote in the Liberal Democratic Party (LDP) to replace unpopular Prime Minister Yasuo Fukuda, who abruptly resigned a week ago as public support dwindled.

Some LDP heavyweights want to hold a snap election soon after the next prime minister takes charge, hoping the new leader would be popular despite a tough environment as the world's second largest economy falters.

Koike said she would pursue free-market reforms, a contrast to front-runner Taro Aso who supports government spending to boost the economy despite a ballooning public debt.

"Backed by calls from the people that we need to continue reforms, I'm making final arrangements to join the presidential election," Koike said.

The election is for president of the LDP, who then becomes prime minister.

Koike, a former defence minister, was due to hold a news conference later in the day to counter Aso, a 67-year-old former foreign minister known for his conservative views on security and love of comic-book culture.

As the LDP prepared for a showdown, the main opposition Democratic Party re-elected its leader, Ichiro Ozawa, unopposed.

The Democratic Party was set to hold its own election on September 21, but no candidates had filed by Monday's deadline to oppose Ozawa, a 66-year-old former LDP heavyweight with a love of bare-knuckles political battle.

Ozawa "will be the first prime minister from the Democratic Party once there are general elections," said Yukio Hatoyama, secretary general of the opposition party.

"We want to topple the government at any cost," Hatoyama told reporters.

The LDP has been in power for all but 10 months since 1955 with strong support from big business and the countryside. But Ozawa led the opposition to a landmark victory last year, seizing one house of parliament amid a backlash over LDP scandals and free-market reforms.

Others running in the LDP race include Kaoru Yosano, 70, the current economic and fiscal policy minister and a staunch advocate of fiscal discipline, and Shigeru Ishiba, 51, a former defence minister.

Yosano warned that the LDP risked collapse without new leadership.

"The LDP will rot away if we carry on like this," Yosano told reporters.

Koike would be the first woman to seek the premier's post in male-dominated Japan, which has some of the world's lowest rates of female representation in politics and business.

A former television journalist who speaks fluent English and Arabic, she said her task was even tougher than that of Hillary Clinton, who narrowly lost her bid to be the first female nominee for the US presidency.

"Ms Hillary used the phrase 'glass ceiling'. It's often a steel sheet in Japan," a smiling Koike told a television talk show on Sunday.

The prime minister must call an election by September 2009. But Makoto Koga, the LDP's election chief, hinted Sunday the vote may come as early as November as the ruling party tries to capitalise on publicity from the leadership race.

A weekend poll of 1,000 voters by the private Asahi network showed support for the LDP has risen amid interest in the contest to replace Fukuda.

Nearly 43 percent of people polled backed the LDP, up from 37 percent in August, while support for the main opposition sagged to 26 percent from 29 percent, according to the survey aired Monday.

- AFP/yt