Federal investigators are "working around the clock" to freeze the assets of mega-fraudster Bernie Madoff's wife, fearing she will try to flee the country or stash the nearly $93 million in her name beyond their reach, sources told The New York Post.

The Securities and Exchange Commission is working with federal prosecutors in Manhattan to prepare a filing asking a judge to formally freeze all of Ruth Madoff's assets as soon as possible.

"The US attorneys will be in court in the next week or so to tell a judge that they believe Mrs. Madoff's assets are derived from ill-gotten gains and that they should be frozen for a certain period of time while the investigation is ongoing," an SEC source said.

The judge will then decide whether there is sufficient reason to believe her assets were legitimately earned or whether they were the proceeds of her husband's $65 billion Ponzi scheme.

"You do not need the case to be nailed down, you just need to be able to convince the judge that there is a strong probability that the funds in question came from crime," the source said.

Ruth, 67, voluntarily agreed to freeze her assets shortly after her hubby was arrested, but the verbal agreement is not legally binding and investigators want to make sure she doesn't try to squirrel anything away now that Bernie has pleaded guilty.

Sources close to Ruth said she and her lawyers expect the filing to be imminent.

Law-enforcement sources also told The Post that the asset freeze would be just the first step in a one-two punch against her as prosecutors work furiously to build a criminal case.

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