TOKYO - JAPAN'S farm minister faced calls on Tuesday to explain himself or resign in a scandal over expenses, dealing a potential new blow to beleaguered Prime Minister Yasuo Fukuda.

Seiichi Ota, a brash ruling party heavyweight appointed just this month, admitted his political support group booked office expenses of 23.45 million yen (S$304,000) despite working out of his secretary's house.

The incident has a hint of political deja vu for the farm ministry, which saw three ministers replaced in 2007 due to money scandals, including one who committed suicide.

Mr Ota admitted not paying rent to his secretary for use of the property, but also failed to explain what the money was really spent on.

'I've been disclosing this information for years because I see no problem,' Mr Ota told a news conference.

'Was it problematic? That's in the eye of the beholder. If people say it is an issue, I must accept that and consider it to be an issue,' he said.

When asked whether he was willing to resign to take responsibility, Mr Ota responded: 'I don't understand the line of questioning.'

Mr Fukuda appointed Mr Ota on Aug 1 as part of a cabinet reshuffle, which has only slightly boosted the government's low approval ratings.

Mr Ota is a veteran lawmaker of the Liberal Democratic Party (LDP), which has been in power for all but 10 months since 1955 and has historically enjoyed strong support from farmers.

The opposition, which controls one house of parliament and is hoping to take power in the next general elections, immediately went on the offensive.

'If he cannot explain himself, then he bears serious responsibility and we would have no choice but to tell him to resign,' said Yukio Hatoyama, the secretary general of the main opposition Democratic Party.

Mr Ota, 62, had already caused controversy during less than a month in office.

He came under fire for saying the government has to pay close attention to food safety because Japanese consumers were 'fussy,' unlike in communist China which could hide uncomfortable truths from its people.

He also faced a furore in 2003 when he said that five university students arrested for gang-raping a woman were in 'good spirits.'

Mr Fukuda, 72, an experienced political operator, took over in September with strong support within the LDP.

But his cabinet's popularity has quickly fallen due largely to the introduction of a deeply unpopular medical plan that raises costs for many elderly people in the rapidly greying country.

Chief Cabinet Secretary Nobutaka Machimura, the government's number two, said he believed Mr Ota would explain in detail what happened.

'Transparency over political funds has always been a major issue for legislators, who bear the responsibility to ensure it,' Mr Machimura said.

'There is no doubt that cabinet ministers carry more significant responsibility than others,' he said.

Under the cabinet of Shinzo Abe, Mr Fukuda's predecessor, farm minister Toshikatsu Matsuoka killed himself in May 2007 just before he was to face a parliamentary grilling over a financial scandal.

Two other farm ministers also resigned under Mr Abe over money scandals, raising questions about the premier's judgement in appointing them. -- AFP