(Repeats to widen distribution)

By Daniel Wiessner

Feb 15 (Reuters) - U.S. prosecutors have subpoenaed one of the women who claims she was sexually harassed by former Fox News chairman Roger Ailes, and compelled her to testify before a federal grand jury, her lawyer said on Wednesday.

New York City lawyer Judd Burstein said his client had received the subpoena on Monday from the securities fraud unit of the U.S. Attorney's office in Manhattan. The subpoena compelled the client's testimony before a federal grand jury, Burstein said.

Reuters was not able to independently confirm the issuance of the subpoena or the existence of either a civil or criminal probe.

The U.S. Attorney's office did not respond to a request for comment. A spokeswoman for Fox News, a unit of Twenty-First Century Fox Inc, said that the network had not received a subpoena.

"We have and will continue to cooperate on all inquiries with any interested authorities," she said.

An attorney for Ailes did not respond to a request for comment. Ailes has previously denied allegations of harassment.

Burstein said prosecutors told him the investigation focuses on alleged sexual harassment at Fox, but declined to elaborate further. He also declined to identify the client who received the subpoena.

It was not clear how the investigation could be tied to securities fraud. Federal securities law requires companies to report legal settlements, including in sexual harassment cases, to the U.S. Securities and Exchange Commission.

Burstein initially made his claim about the subpoena at a court hearing earlier on Wednesday in a sexual harassment lawsuit he filed on behalf of Fox anchor Andrea Tantaros, whom he said was not the subject of the subpoena.

Ailes resigned last year after former Fox News anchor Gretchen Carlson filed a lawsuit against him claiming she was harassed and had her contract canceled when she rebuffed Ailes' advances. The network agreed to pay $20 million to settle the case on behalf of Ailes, who denied any wrongdoing.

At the time, Ailes received a severance package of about $40 million, according to a source familiar with the situation, who asked to remain anonymous.

Tantaros made similar claims in her lawsuit, which was sent to arbitration. Unlike Carlson, she also sued Fox.

Carlson's lawyer, Nancy Smith, said on Wednesday that she had not received any subpoenas related to sexual harassment claims against the network.

(Reporting by Daniel Wiessner; editing by Noeleen Walder and David Gregorio)