LOS ANGELES (AP) _ Federal officials have overcome major legal obstacles in their case against Ferdinand Marcos and it is now likely they will ask a federal grand jury to indict the former Philippine president for fraud, the Los Angeles Times reported today.

However, the indictment is expected to deal only with accusations of wrongdoing after Marcos left office in February 1986, the newspaper said.

The case was narrowed to overcome doubts about whether U.S. law could apply to the deposed president's alleged efforts to misappropriate billions of dollars in Philippine taxpayers' funds, according to anonymous sources cited by the newspaper.

The indictment, anticipated for months, has been delayed by a number of circumstances.

Acting Associate Attorney General Francis A. Keating II expressed reservations at one point about the quality of the case when draft charges were brought before him.

The investigation is now focusing on allegations that Marcos and his wife, Imelda, conspired with Saudi Arabian financier Adnan Khashoggi and others to violate U.S. district court injunctions. They allegedly secretly transferred ownership of hundreds of millions of dollars in stolen art and Manhattan real estate bought with Philippine government funds.

Court records in related civil lawsuits allege that Marcos took control of the funds while he was still in power but used elaborate schemes involving front companies and agents to hide his ownership and liquidate properties after he went into exile in Hawaii.

The inter-agency Police Review Group, which became more prominent in the wake of the diplomatically embarrassing attempt to prosecute Panamanian strongman Manuel A. Noriega on federal drug charges in Florida, helped settle problems with the legal case early in the week, the Times said.

U.S. Attorney Rudolph W. Giuliani in New York, along with his staff, outlined details of proposed criminal charges against Marcos at a White House meeting of the review group Tuesday, The Times said. President Reagan did not attend.

Intelligence advisers are expected next week to offer their opinions on how the case could affect foreign relations.

In a statement issued from the Philippine embassy in Washington, D.C., Severina Rivera, general counsel for his government's Presidential Commission on Good Government, said:

''There has been considerable skepticism in Manila about President Reagan's willingness to approve the indictment of Mr. Marcos. ... If he approves it, Filipinos everywhere will applaud Mr. Reagan and the American system of justice that applies the full force of the law to corrupt dictators who violate U.S. laws.''

However, some concern has been expressed that Marcos may flee to Mexico or another country because the indictment is imminent, a source told The Times.