“Al Jazeera Media Network under cyber attack on all systems, websites & social media platforms,” Al Jazeera News said on Twitter on Thursday afternoon.

About an hour later the Al Jazeera News website followed up by saying: “The websites and digital platforms of Al Jazeera Media Network are undergoing systematic and continual hacking attempts. These attempts are gaining intensity and taking various forms.”

“The platforms have not been compromised,” the post added.

A person familiar with the matter, who requested anonymity because the source was not authorized to speak to the press, told Fortune that the network is facing a distributed denial of service attack, which involves trying to overload computer servers with bogus Internet traffic. The source said the attack seems to involve the Mirai botnet that surfaced at the end of last year, when it led to an Internet blackout for many major sites in the northeastern U.S.

Al Jazeera has not specified the type, or types, of attack.

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Last month hackers gained access to the website of Qatar News Agency, the official media outlet of the Middle East nation, and reportedly planted false statements attributed to Qatari emir Sheikh Tamim bin Hamad al-Thani. The comments, which criticized U.S. President Donald Trump and praised Iran for providing stability in the Middle East, caused a rift between Qatar and its neighboring states.

Several Gulf nations including Saudi Arabia, Egypt, and the United Arab Emirates cut off diplomatic and economic ties with Qatar as a result.

U.S. investigators said they believe Russian hackers were behind the earlier hack, according to a CNN report.