Updated

Oksana Grigorieva spent tens of thousands of dollars in PR to thwart public perception that she sold the secret tapes -- and now she wants Mel Gibson to foot the bill ... sources tell TMZ.

We're told Oksana racked up $84,000 in PR expenses and certain unpaid legal fees. As for the PR fees, TMZ sources say Oksana felt hiring PR reps was the only way counter someone as big and powerful as Mel Gibson. Oksana -- who insists she didn't sell the tapes -- felt she was getting trashed in the media.

Sources say Oksana wants Judge Scott Gordon in the custody/child support case to clear the $84,000 debt.

Here's the disconnect.

The judge would never award money for PR expenses. Aside from legal fees, Judge Gordon would adjust the existing agreement -- $5,000 a month plus the house -- only based on the needs of baby Lucia.

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As TMZ first reported, Oksana's lawyers have gone to court and asked Judge Gordon to up the monthly child support obligation to upwards of $40,000.

TMZ is told the judge has yet to rule on the request.