Recent Treasury regulations intended to prevent abuses of the $1.2 billion-a-year foreign tax credit have come under heavy attack from the oil and banking industries.

Under industry pressure, Republicans on the Senate Finance Committee are seeking to block proposed new Internal Revenue Service regulations that would limit use of the tax credit.

At the same time, industry leaders are mounting a campaign to persuade Treasury Secretary G. William Miller, himself a former businessman, to withdraw the IRS regulations voluntarily and order the agency to soften them.

Although the Treasury and the industries differ widely on what is at stake, some congressional analysts estimate the outcome could raise or lower U.S. corporate tax payments by $500 million to $1 billion a year.

The skirmish involves a series of IRS rulings issued over the past two years, first preventing U.S. oil firms from claiming tax credits here for overseas royalty payments, then further restricting which foreign taxes qualify.

The Carter administration contended last June that these regulations would not have much impact on U.S. corporations' tax bills because ultimately foreign countries would alter their tax structures to conform to the regulations.

However, oil industyr leaders complain that the regulations are drafted so tightly that virtually no taxes now paid by their foreign affiliates would qualify for U.S. credit, costing them millions a year.

Under the foreign tax credit provisions, American firms may reduce their U.S. taxes on income earned abroad by the amount of taxes they pay the foreign government involved. The aim is to avoid double taxation.

Rawleigh Warner Jr., chairman of Mobil Corp., wrote Miller to complain that if the new regulations are allowed to go into effect, there "will be double taxation" of U.S. firms -- by the federal and overseas governments.

The Finance Committee Republicans, led by Sen. Robert Dole (Kan.), hope to add an amendment to the panel's pending "windfall profits" tax bill that would delay the IRS regulations until September 1980.

If Miller could be persuade to withdraw the regulations on his own, GOP sources say, the senators would drop their effort, but others say Miller is unlikely to budge.

The skirmishing has intensified in recent days, in part because the industries involved are just beginning to realize the extent of the new IRS rulings and in part because the proposal's effective date is approaching.

The current Treasury timetable calls for critics to have formal comments in by Sept. 30, and the department will hold hearings Oct. 11. The provisions could become effective this fall.

Under the new regulations, a tax imposed by a foreign government would not qualify for the U.S. tax credit unless it meets a series of stiff tests designed to ensure that it is not merely a royalty imposed only on American firms.

Industry representatives are particularly concerned about a provision that would deny the credit in cases where a company claims credit for non-income taxes it pays a foreign government.

The effort comes just as House liberals are struggling -- without much success -- to force still further crack-downs on the foreign tax credit, citing it as a major area of abuse.

Issuance of the new Treasury regulations last June was in part an attempt to fend off moves in the House to repeal the credit entirely. Most economists have argued that would be a mistake.

However, the liberals have not gotten very far. Although the House voted during its debate on the budget last spring to repeal the credit, that vote was largely symbolic.

Efforts by the liberals to raise the issue in the House Ways and Means Committee have become mired. A meeting last week to begin consideration of a liberal proposal fell through for lack of support.

The foreign tax credit has long been a major target of "tax reform" advocates, who contend that oil companies have been reaping a windfall by claiming tax credits here for royalties paid abroad.

The IRS issued rulings in early 1978 that would prohibit oil companies from claiming U.S. tax credits for payment of foreign royalties, but, to the dismay of some critics, the crackdown affected only future cases.