OSAKA — The Osaka Prefectural Assembly’s General Affairs Committee gave its approval Thursday to a controversial bill to impose a 3 percent tax on the gross profits of large banks operating in the prefecture.

The bill is almost certain to be adopted by a plenary session Tuesday.

The new tax plan, which is modeled on the one introduced last month in Tokyo, calls for banks with 5 trillion yen or more in assets to be subject to a maximum 3 percent tax on their gross profits. If enacted, 26 banks will be affected by the new measure, which is expected to take effect next April.

The bill, proposed by the Liberal Democratic Party, was endorsed on a tie-breaking vote by Nariaki Hata, a member of the LDP who chairs the committee.

In addition to the LDP, the Japanese Communist Party and Social Democratic Party voted in favor of the bill, while New Komeito and the Democratic Party of Japan voted against it, attempting to carry it over to the September assembly session.

The three parties that backed the bill hold a majority in Osaka’s 112-seat assembly, making it certain that the bill will be passed at Tuesday’s plenary session.

The cash-strapped prefectural government estimates the new tax will increase local tax revenues by 37 billion yen.

However, roughly 80 percent of the increase is expected to be offset by a decline in grants from the central government, leaving a net increase of only 7.5 billion yen a year.

For Tokyo, which does not receive grants from the central government, the same measure is expected to bring an extra 110 billion yen into its coffers.

Unlike Tokyo, however, the bill has one more hurdle to jump before it can become law — Osaka Gov. Fusae Ota.

Even if the tax plan is adopted by the prefectural assembly, Ota can still theoretically veto it based on Article 176 of the Local Autonomy Law. Once a plan is vetoed, it can only be overruled by a vote of more than two-thirds of the assembly.

After Thursday’s decision, Ota said the committee’s discussions of the bill were inadequate and that she would ask the assembly to consider it again carefully.

The tax plan was initially submitted on the final day of the March session, and the committee held three sessions before putting it to a vote.

At one session held Monday, Kaneo Muromachi, president of Sanwa Bank and chairman of the Osaka Bankers Association, spoke as an invited witness and said the association would be forced to consider legal action against the prefecture if the new tax is introduced.

In Tokyo, the Japanese Bankers Association is already preparing a lawsuit, he said.

Economic organizations in Osaka also oppose the new tax.