TOKYO - JAPAN'S transport minister was in the hot seat on Saturday after calling a teachers' union a 'cancer", the latest in a series of contentious remarks as new Prime Minister Taro Aso ponders calling a snap election.

Mr Aso, an outspoken nationalist who favours spending and tax cuts to boost Japan's faltering economy, took office on Wednesday and is widely expected to call an early election to try to break a policy deadlock due to a divided parliament, where the opposition controls the upper house and can delay laws.

But support for Mr Aso's cabinet fell short of 50 per cent in several media polls published on Friday, lower than his predecessor Yasuo Fukuda enjoyed when he took the job and casting doubt on Mr Aso's ability to lead his party to an election win.

In a fresh headache for Mr Aso, new Transport Minister Nariaki Nakayama on Saturday called the Japan Teachers Union 'a cancer for Japan's education system' and vowed to destroy the left-leaning group.

'I will stand at the forefront to destroy the Japan Teachers' Union, which is a cancer for Japanese education,' Mr Nakayama told reporters after a meeting of ruling party members in southern Japan.

Mr Nakayama, 65, had already gotten off to a rocky start when he had to apologise and withdraw comments made in interviews with media including a remark that Japan was 'ethnically homogeneous", a comment that drew protests from Japan's Ainu indigenous people.

The comments sparked calls from the opposition for Mr Nakayama to resign and prompted Chief Cabinet Secretary Takeo Kawamura to warn ministers to watch what they said.

Asked on Saturday whether he would resign, Mr Nakayama told reporters he would decide himself after talking with his wife.

Mr Nakayama was a staunch advocate of revising Japan's basic law on education to put more emphasis on teaching patriotism and traditional values. The reforms, opposed by the Japan Teachers' Union, were enacted in 2006.

He also heads a group of LDP lawmakers that declared the 1937 Nanjing Massacre a fabrication.

China says Japanese troops killed 300,000 people in what was then the capital, while an Allied tribunal put the death toll at about 142,000. -- REUTERS