TOKYO - Support for Japanese Prime Minister Yoshihiko Noda's government dropped by 10 points to 55 percent one month after he took office, with more than half opposing planned tax increases for post-quake restructuring efforts, a poll showed on Monday.

Noda, who became the country's sixth prime minister in five years, had gained strong support shortly after taking office in early September -- a sharp turnaround from his unpopular predecessor, Naoto Kan, who saw his support fall below 20 percent.

But just after a week in office, Noda was forced to fire his trade minister due to gaffes.

The disapproval rating for his government rose to 29 percent, the survey by Yomiuri newspaper showed, up 10 points from the previous month's poll.

Noda, a fiscal hawk who favours raising taxes to increase government revenue, has promised swift fiscal reforms to cope with the massive public debt -- now twice the size of Japan's $5 trillion economy -- but with an eye on growth.

The survey of 1,036 respondents showed that 55 percent were against the government's plan to raise income and corporate taxes to support the restructuring of northeastern Japan hit hard by the devastating March 11 earthquake and tsunami.

It showed 38 backed the tax hike plans.

The March disaster triggered the world's worst nuclear crisis since Chernobyl in 1986, heating up debate in Japan over its future energy policy.

The survey showed 48 percent supported Noda's plan to restart nuclear power plants that have completed routine inspections, while 38 percent opposed the idea.

Japan's is aiming to launch this month its public-private panel chaired by Noda for devising long-term policies spanning economic, trade and energy that it hopes will wield considerable clout in running the country.  

The panel is expected to discuss whether to join negotiations on a US-led free trade pact, called the Trans-Pacific Partnership (TPP).

The Yomiuri poll showed 51 percent said Japan should join the TPP talks, while 23 percent were against the idea.

Many Japanese businesses are keen to join the TPP, which could add growth, though farming lobbies have resisted the move as it would lower barriers to goods and services from overseas.

Noda said on Monday the government would make a decision on whether to join the TPP talks in the near term after launching formal discussions on the issue on Tuesday, Kyodo news agency reported.