Nine US State Department officials were targeted by the Israeli spyware Pegasus, US news outlets reported on Friday. Spyware developer NSO Group said it was investigating claims that its technology was used to hack the phones of US officials in Uganda.

Reuters news agency cited four sources who said that nine US diplomats had been targeted. The Associated Press reported that 11 officials had their iPhones hacked.

It was unclear who was behind the alleged cyberattack.

The hacking is the first known instance of Pegasus spyware being used against United States government personnel.

'Serious risk to US personnel'

"We have been acutely concerned that commercial spyware like NSO Group software poses a serious counterintelligence and security risk to US personnel,'' White House press secretary Jen Psaki said at a briefing on Friday.

NSO said it was willing to cooperate. "On top of the independent investigation, NSO will cooperate with any relevant government authority and present the full information we will have," the firm said in a statement.

NSO Spyware known as Pegasus has reportedly been used to spy on activists and journalists and turns phones into pocket spying devices. 

In November the US government announced that it would  impose export limits on the company, saying that its tools "enabled foreign governments to conduct transnational repression."

jsi, kb/aw (AFP, Reuters)