An official of Iran's Telecommunications Infrastructures Company on Saturday said a cyberattack "temporarily" disrupted Internet services but was repelled by Iran's home-grown firewall DEZHFA.

Sadjad Bonabi who made the announcement in a tweet on Saturday morning said the disruption affected some mobile operators as well as home internet providers. According to Bonabi who is a member of the board of directors of the Telecommunication Infrastructures Company owned by the Ministry of Telecommunications, the attack was repelled by DEZHFA, a home-developed firewall.

In a tweet the Internet watchdog Netblocks said that from11:45 a.m. local time the national connectivity in Iran had fallen to 75% after authorities reportedly activated "Digital Fortress" isolation mechanism. Net blocks said the incident is ongoing.​

In another tweet three hours later Bonabi said all Internet operators affected by the attack were stabilized.

According to Bonabi the partial blackout was caused by a DDoS attack in which a perpetrator seeks to make a network unavailable to its intended users by disrupting services of a host connected to the Internet. In this type of attack hackers send too many requests to the Internet protocols (IPs) of a country and the overload causes disruption or crashes the network.

Nariman Gharib, a UK-based journalist and Internet freedom activist in a tweet said the botnet attack on Iranian Internet infrastructures was "massive". In another tweet Gharib also pointed out that the time of the attack coincided with the day Iran intended to launch its Zafar satellite. The plan was postponed on Saturday without further explanation.

Speaking to Mehr News Agency later Bonabi said the attack originated in East Asia and North America but did not seem to be conducted by another government and was the work of hackers.