Prime Minister Yoshihiko Noda has decided to dissolve Japan's parliament as early as Friday, with an election possibly next month, media said Tuesday, a move likely to unseat him from power.

Noda will call an election for as early as December 16 or as late as January 20, according to major Japanese news media, including the Nikkei business daily and the liberal-leaning Asahi Shimbun.

After months of speculation over the date of the next national ballot, the issue surged to the fore on Monday afternoon, with Noda seen pushing a plan to join a vast trans-Pacific free trade deal as one of his core campaign pledges.

That would mark his Democratic Party of Japan (DPJ) out from the main opposition party, who are largely against the pact.

"Prime minister decides to dissolve parliament this year," the frontpage headline of the influential Nikkei business daily said Tuesday.

"The groundwork toward parliamentary dissolution is moving forward," the newspaper said.

The Mainichi Shimbun said the premier could dissolve the lower house on Friday and hold an election on December 9.

Noda declined to discuss when he would call an election when pressed during a parliamentary session.

Polls must be held by next summer when the four-year term of the current parliament expires.

Noda is widely expected to have an uphill battle to get his DPJ re-elected in the face of widespread voter disillusionment with the party's record in the three years since they ousted the long-ruling Liberal Democratic Party.

In the latest Asahi Shimbun poll released Tuesday, the approval rating for the Noda cabinet slipped to mere 18 percent while the disapproval rating rose to a whopping 64 percent.

An election defeat would mean Noda, who took office in September 2011, would become the sixth Japanese leader to leave the prime minister's residence after spending roughly a year in office.

Noda's predecessors in the current parliament, Yukio Hatoyama and Naoto Kan, both resigned amid low approval ratings and power struggles within the DPJ.

With a short election cycle and fickle public opinion, Japan has changed leaders almost annually since Junichiro Koizumi, who led the nation for more than five years to September 2006.

The regular changes at the top have led to handwringing over Japan's diminishing influence on the world stage, as well as the country's sliding economic status after it was overtaken by China as the world's second largest economy.

Noda's decision on the exact timing of an election will be determined in part by how the US reacts to overtures about Japan's fulsome participation in the Washington-backed Trans-Pacific Partnership (TPP), the Nikkei said.

The TPP is seen as a key plank in Barack Obama's pivot to Asia and a counterweight to the growing clout of China.

It presently includes Australia, Brunei, Canada, Chile, Malaysia, Mexico, New Zealand, Peru, Singapore, the US and Vietnam. (AFP)