FILE PHOTO -- The ticker and trading information for Blackstone Group is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) April 4, 2016. REUTERS/Brendan McDermid/File Photo

(Reuters) - Digital rights group Access Now on Thursday began circulating a petition urging Blackstone Group to abandon any plan to invest in Israeli firm NSO Group, a maker of spyware for mobile devices, following a report that such a deal may be imminent.

Israel’s Calcalist business newspaper on Sunday said that Blackstone is in advanced talks to pay $400 million for 40 percent of privately held Israeli firm NSO Group.

NSO has come under international scrutiny in recent months amid allegations the Mexican government has used NSO’s Pegasus mobile spyware to illegally target private citizens. Mexico’s government is investigating the claim, though Mexican President Enrique Pena Nieto has said the accusations are false.

Access Now said on Thursday it has begun seeking signatures for the petition, which urges Blackstone to immediately drop plans to invest in NSO Group and its surveillance technology. It asks the investment firm to agree to a plan to ensure its current and future investments do not “facilitate human rights violations.”

Cyber researchers with Citizen Lab at the University of Toronto’s Munk School of Global Affairs said last month the Mexican government tried to install Pegasus software on devices belonging to opposition lawmakers as well as private citizens including human rights lawyers and journalists.

Citizen Lab, which has released five reports on surveillance campaigns conducted with NSO’s surveillance software, on Wednesday asked Blackstone’s board of directors to reconsider the deal.

“We urge you to carefully consider the human rights and ethical implications of an investment in a spyware company such as NSO Group,” Citizen Lab Director Ronald Deibert said in a five-page letter to the board.

Private equity firm Francisco Partners in 2014 paid $120 million to acquire a majority stake in NSO, which was founded in 2009 by Omri Lavie and Shalev Hulio.

Representatives for Blackstone and NSO could not immediately be reached for comment.