Google says it has detected and stopped thousands of phishing attacks targeting email accounts of Iranian users ahead of the 14 June presidential election.
In an online statement, the firm said it had noticed a "significant jump" in the region's overall volume of phishing activity in the last three weeks before the election.
The timing and targets suggested the attacks were "politically motivated". Google's vice-president of security engineering, Eric Grosse, said the phishing attacks originated from within Iran. Phishing attempts to obtain passwords and other private computing information by directing users to fake websites.
"For almost three weeks, we have detected and disrupted multiple email-based phishing campaigns aimed at compromising the accounts owned by tens of thousands of Iranian users," he said. Mr Grosse warned Iranian users to take extra measures to protect their accounts from "state-sponsored attacks".
It is not the first time that Iranian internet users have come under cyber-attack, but there seems to have been a surge in recent days, which could be related to the presidential election.
Usually the targets of these attacks are journalists or activists, both in Iran and abroad. Since the disputed election of 2009, the Iranian authorities have tightened access to the internet, because of its widespread use by protestors at the time. At times of possible unrest, the internet in Iran has almost come to a halt.