TOKYO - A new poll shows that Japanese Prime Minister Naoto Kan's public approval rating has fallen to the lowest level since he took office last year.

The survey by Kyodo News agency released Sunday found that 15.8 per cent of respondents approve of the embattled leader's Cabinet, down from about 17 per cent a month earlier.

Kan faces increasing demands to step down amid criticism of his handling of the March 11 earthquake and tsunami and subsequent accident at the Fukushima Dai-ichi nuclear plant. Critics accuse him of a lack of leadership, while survivors complain of slow relief and recovery efforts.

Kan has said he will quit after two key bills are approved in parliament, which is likely to happen this month. That would set the stage for a leadership election within Kan's ruling party and a new prime minister -- Japan's sixth in four years.

With his days numbered, Kan recently scrapped plans to visit President Barack Obama in Washington next month.

Finance Minister Yoshihiko Noda and trade and industry minister Banri Kaieda are among the reported front-runners to succeed Kan.

But it was former Foreign Minister Seiji Maehara who emerged as the favourite in Kyodo's nationwide telephone poll, with the support of 28 per cent of respondents. Maehara, who resigned in March over an illegal political donation, has not declared his candidacy.

Almost two-thirds of the 1,016 respondents said the most important goal for the new government is the recovery of disaster-ravaged northeastern Japan. A third of those surveyed said they want to see improvements in the economy and jobs.

Although voters have soured on Kan, they overwhelmingly approve of his new policy of gradually phasing out nuclear power. More than 75 per cent of respondents said they want the incoming administration to continue that policy.

Kyodo said it conducted the survey of eligible voters on Saturday and Sunday. It did not release a margin of error, but a poll of that size would typically have a margin of error of about 5 percentage points.