Chief Cabinet Secretary Shinzo Abe has expanded his lead among voters in the race to become Japan's next prime minister, an opinion poll released on Tuesday showed.

Japanese Chief Cabinet Secretary Shinzo Abe fields questions at a hotel in Tokyo, May 29, 2006. Abe tops the list of politicians seen by retail investors as being best suited to become Japan's next prime minister, a Reuters survey shows. [Reuters]

But a separate survey found that major Japanese businesses prefer Abe's nearest rival, who is seen as better at improving relations with China.

Abe, 51, a popular political blue-blood known for his tough stance towards China and North Korea, has steadily topped the list of politicians whom voters say they would like to see succeed Prime Minister Junichiro Koizumi, who is set to step down in September.

According to a nationwide survey conducted at the weekend by the Asahi newspaper, 45 percent of voters support Abe, a rise of 4 percentage points from the previous poll in May.

At the same time, support for key rival Yasuo Fukuda, a 69-year-old veteran lawmaker, slipped by 4 percentage points from the May poll to 25 percent.

Neither politician has formally said he will stand in an election for president of the ruling Liberal Democratic Party to be held in September.

The party president is expected to become prime minister by virtue of the LDP's majority in parliament's powerful lower house.

A majority of Abe's supporters in the Asahi poll said they wanted him to be Japan's next prime minister because of his "good personality and image".

Only 5 percent of respondents said Foreign Minister Taro Aso, 65, was best suited for the job, while Finance Minister Sadakazu Tanigaki, 61, garnered 3 percent.

Japan's relations with China and South Korea have become a focal point in the race to succeed Koizumi, who critics say is responsible for worsened ties with the two Asian neighbours because of his annual visits to Tokyo's Yasukuni shrine, where convicted war criminals are honoured along with the nation's war dead.

Abe has defended Koizumi's visits to the Shinto shrine but has not made clear whether he do so himself if he became prime minister. Fukuda favours building a new, secular memorial.

Fukuda has criticised Koizumi's Asian diplomacy and stressed the need for Japan to improve diplomatic relations with China and South Korea.

A separate survey of major businesses, conducted earlier this month by the Asahi, showed Fukuda was the favourite among Japanese business leaders.

Of 31 firms polled, 15 said they wanted Fukuda to succeed Koizumi, while 12 said they backed Abe.

"In view of future diplomacy with countries, especially China, we have expectations for Fukuda's abilities," the Asahi quoted one respondent as saying.

A poll released by the Yomiuri newspaper on Tuesday found that 79 percent of respondents said Japan should attach more importance to Asian diplomacy.

But 46 percent of respondents to the same poll said Koizumi's successor should visit Yasukuni, while 43 percent were opposed.

In addition, 51 percent did not think Koizumi's successor should avoid Yasukuni visits in order to improve ties with China.