Tokyo - Former Japanese foreign minister Taro Aso, the top contender for succeeding newly resigned prime minister Yasuo Fukuda, Friday promised measures to kick-start Japan's lacklustre economy.

When officially announcing his candidature for the September 22 election for the presidency of Japan's ruling Liberal Democratic Party (LDP), the 67-year-old party hawk promised to "dispel the concerns of the population."

Frustrated by low poll ratings and the opposition blocking his policies in Japan's upper house, Fukuda unexpectedly announced his resignation on Monday.

Critics fear that under Aso, who as LDP president would be de-facto prime minister, Japan would return to high-spending policies despite its huge public debt.

Aso plans to detail his policies by Wednesday, the official kick-off of internal party campaigning. His support of economic stimulus measures does not meet with undivided support from within the LDP.

Supporters of a stricter spending discipline fear that under Aso's leadership the world's second largest economy, which is fighting against recession, could completely veer off the reform course set by former prime minister Junichiro Koizumi.

Also vying for the top post are Economic Minister Kaoru Yosano, former defence minister Yuriko Koike and a former LDP policy chief Nobuteru Ishihara.

"The main point is whether we can promote structural reform," said former TV anchor Koike.

Distancing himself from Aso, Ishihara said "Mr Aso's views are not the views of the LDP.

Several other names also made the rounds on Friday. The LDP, which has been ruling Japan almost continuously for the past 50 years wants to prevent the impression that the outgoing premier secretly promised his job to Aso, leading party members to support the open contest between several candidates.

However, the anti-Aso camp sees its chances dwindling if there are too many contenders. The winner not only gets the party presidency, but is also de-facto prime minister, as the LDP and its coalition partner, the New Komeito party enjoy a comfortable majority in Japan's powerful lower house. (dpa)