Two senators investigating two massive data breaches at Yahoo have raised concern at the company's apparent lack of "willingness to deal" with members of Congress.

Sens. John Thune (R-SD) and Jerry Moran (R-KS) wrote to Yahoo chief executive Marissa Mayer on Friday to ask for more information about two cyberattacks, which led to the theft of a billion-and-a-half records.

But so far, the company has been less than cooperative, the senators said.

The letter said that the members of the Senate Commerce, Science, and Transportation Committee, charged with investigating the cyberattacks, said the company had "thus far been unable to provide answers to many basic questions" about the breach, despite several inquiries.

It added that a "last-minute cancellation" by Yahoo staff to members of the committee last month "prompted concerns about the company's willingness to deal with Congress with complete candor about these recent events."

The letter was filed followed near-complete silence from Yahoo -- after it admitted it was hit by state-sponsored attackers on two separate occasions. Yahoo revealed in September the theft of 500 million records, then thought to be the largest theft of records in history, only to reveal in December a separate theft of one billion records.

News of the breaches came just as Verizon was closing the $4.8 billion purchase of Yahoo.

As of the company's third-quarter earnings in January, Verizon reaffirmed its commitment to buying Yahoo, but said it would seal the deal later in the year.

Yahoo has until Feb. 23 to respond to a number of questions posed by the senators, one of which specifically asks about Yahoo's remediation efforts.

A Yahoo spokesperson would not say if the company will respond to the senators.

"We're in receipt of the letter, reviewing it, and will respond as appropriate," the spokesperson said.

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