(JTA) – A number of Israeli websites were victims of a cyberattack on Thursday morning, May 21, by a group of hackers to mark Al-Quds Day. “The countdown of Israel destruction has begun since a long time ago,” reads the warning message in Hebrew and broken English. The words are accompanied with images of a destroyed Tel Aviv, links to anti-Israel YouTube videos and more threatening phrases. Some Israeli re-ports said hundreds of websites were attacked on the eve of Jerusalem Day, though the National Cyber Bureau said that “a host of Israeli websites were hacked in the morning hours in a suspected Iranian cyberattack.”

Al-Quds Day, which was first declared by Iran in 1979, is marked throughout the Arab world with demonstrations against Israel and expressing support for Palestinians. It is held on the last Friday of Ramadan. Jerusalem Day marks the reunification of Israel’s capital in 1967. The handful of hackers, calling themselves Hackers of Saviour, are from Turkey, North Africa and the Gaza Strip and have been active since last month, the information security firm Check Point told Israel’s Kan public broadcaster.

Government websites were not attacked, according to the National Cyber Bureau. The bureau said it was notified last week that there were likely to be cyberattacks on Israel to mark Al-Quds Day, as there have been in previous years.

The affected websites appear to come from private servers of one private company, according to the bureau, which Ynet’s Calcalist business website identified as Upress.

The hacking comes after back-and-forth attacks alleged to be between Israel and Iran. In April, Iran launched a cyberattack on Israel’s civilian water system. Israel has been blamed for a cyberattack earlier this month on Iran’s Shahid Rajaee port, which snarled cargo traffic for days.