Tokyo  - Japan's political leaders on Tuesday officially began campaigning for seats in the House of Representatives, in an election which could bring an end to the Liberal Democratic Party's (LDP) more than half a century in power.

"The ability to take responsibility and the ability to implement (polices) is the point I would like to stress," Prime Minister Taro Aso was quoted as telling a crowd in western Tokyo Tuesday ahead of the lower-house election slated for August 30.

The party's president, who suffers from low popularity ratings, stressed the government's efforts to pull the world's second-largest economy out of recession with a record-high stimulus package.

Aso said Japan's economy has shown signs of improvement, with growth generated in the last quarter after five quarters of contraction.

The LDP's popularity has been on the decline since the last general election in September 2005, when the charismatic former prime minister Junichiro Koizumi led the party to a landslide victory.

The LDP has gone through four premiers in four years - Koizumi, Shinzo Abe, Yasuo Fukuda and Aso.

While the birth-rate remains low and the average age of the population gets higher, the income gap has been widening. The national debt is mounting and is now more than 160 per cent of gross domestic product.

The main opposition Democratic Party of Japan (DPJ) considers the upcoming election an opportunity for change.

"The day to make history has finally come," party president Yukio Hatoyama was quoted as saying in a speech in the western city of Osaka. "Please give the DPJ the power to change the government. We will start a new politics without depending on bureaucrats."

The party needs 129 more seats to secure 241-seat majority in the lower house.  (dpa)