After the Pegasus mystery, the finger of suspicion points to a government agency, senior Congress leader P Chidambaram said on Wednesday, a day after several opposition leaders claimed they were alerted by Apple about a "state-sponsored" attack on their iPhones.

At the moment, it is only a suspicion, Chidambaram said.

"It is undeniable that hundreds of Opposition leaders got an alert from Apple of a state-sponsored attempt to compromise their phones. Why only Opposition leaders? Who will be interested in compromising the phones of Opposition leaders," the former Union home minister said.

"After the Pegasus mystery (not resolved until this date), the finger of suspicion points to a government agency. At the moment it is only a suspicion," the Congress leader said.

Several opposition leaders on Tuesday claimed they received an alert from Apple warning them of "state-sponsored attackers trying to remotely compromise" their iPhones and alleged hacking by the government, a charge rejected by IT Minister Ashwini Vaishnaw.

The minister assured a thorough probe into the matter.

Those who received such notifications include Congress chief Mallikarjun Kharge, party leaders Shashi Tharoor, Pawan Khera, K C Venugopal, Supriya Shrinate, T S Singhdeo and Bhupinder S Hooda; Trinamool Congress MP Mahua Moitra; CPI(M) general secretary Sitaram Yechury and Samajwadi Party chief Akhilesh Yadav.

Shiv Sena (UBT) MP Priyanka Chaturvedi, AAP's Raghav Chadha, AIMIM president Asaduddin Owaisi and some aides of Congress MP Rahul Gandhi also received the notification.

Yechury and Chaturvedi wrote to Prime Minister Narendra Modi while Moitra shot off a missive to Lok Sabha Speaker Om Birla, raising concerns over the issue and demanding action.

Reacting to opposition leaders' claims, iPhone maker Apple Inc said it is possible that some threat notifications may be false alarms and some attacks may not be detected.

It, however, refused to say what triggered warnings received by the opposition leaders.

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