Google has denied that it is preventing a Texas investigation into whether it is abusing its dominance of the internet search market.
It comes after Texan attorney general Greg Abbott accused the company of improperly refusing to hand over evidence he had requested, totalling more than 14,500 documents.
Google said it had "shared hundreds of thousands of documents" with Mr Abbott.
Mr Abbott is asking a judge to order Google to release the relevant files.
The dispute over the missing documents centres on whether they are communications between Google employees and the company's lawyers.
If that is the case then they are protected by attorney-client privilege and do not need to be released.
Mr Abbott accuses Google of trying to hide documents that do not fall under such legal protection.
The dispute in Texas comes two months after US watchdog, the Federal Communications Commission (FCC), fined Google $25,000 (£15,700) after it ruled that the company had held back an investigation into Google's Street View mapping feature.
The FCC said Google had "deliberately impeded and delayed" the investigation for months, by not responding to requests for information and documents.
Google disputed the FCC's findings.
The company is also continuing to face anti-competition investigations in a number of other US states.
In addition, the European Commission said last month that Google had to take action to allay concerns that it is abusing its dominant position.
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