The United States used U.S.-Israeli spy software to hack into the French presidential office earlier this year, the French cyberwarfare agency has concluded, according to the newsmagazine l’Express.

The magazine reported late Tuesday that the computers of several close advisers to then-president Nicolas Sarkozy – including Chief of Staff Xavier Musca – were compromised in May by a computer virus that bears the hallmarks of Flame, which was allegedly created by a U.S.-Israeli team to target Iran’s nuclear program. Anonymous French officials pointed the finger at the United States.

“You can be on very good terms with a ‘friendly’ country and still want to guarantee their unwavering support – especially during a transition period,” an official told the magazine. The alleged spying attack took place a few days before the second round of the French presidential elections, which Sarkozy lost to Francois Hollande, a socialist.