Bahrain and Egypt on Thursday apparently joined Saudi Arabia and the United Arab Emirates in blocking access to websites run by the pan-Arab satellite network Al-Jazeera, part of a growing regional dispute with Qatar after an alleged hack of its state-run news agency.

The alleged hack and a purported fake news report that was published during it have exposed real tensions still lingering in the Gulf between Qatar and other nations over the small gas-rich country's support of Islamist groups.

While Qatar quickly denied the comments in the fake report attributed to ruling emir Sheikh Tamim bin Hamad Al Thani, Saudi-owned satellite channels repeatedly aired them throughout the day Wednesday. The incident revived suspicions that exploded into the open three years ago, when several Gulf nations pulled their ambassadors from Qatar over similar worries about its politics.

The alleged hack happened early on Wednesday morning and hours later, the website of the Qatar News Agency still was not accessible.

The fake article quoted Sheikh Tamim as calling Iran an “Islamic power” and saying Qatar's relations with Israel were “good” during a military ceremony.

Online footage of Qatari state television's nightly newscast from Tuesday showed clips of Sheikh Tamim at the ceremony with the anchor not mentioning the comments, though a scrolling ticker at the bottom of the screen had the alleged fake remarks. They included calling Hamas “the legitimate representative of the Palestinian people,” as well as saying Qatar had “strong relations” with Iran and the United States.

“Iran represents a regional and Islamic power that cannot be ignored and it is unwise to face up against it,” the ticker read at one point.

The hackers also purportedly took over the news agency's Twitter feed and posted alleged quotes from Qatar's foreign minister accusing Arab nations of fomenting a plot against his country. A series of tweets said Qatar had ordered its ambassadors to withdraw from Bahrain, Egypt, Kuwait, Saudi Arabia and the United Arab Emirates over the plot. The tweets were later deleted.

Sheikh Saif Bin Ahmed Al Thani, the director of the Qatari government's communications office, issued a statement saying authorities had launched an investigation.

“The statement published has no basis whatsoever and the competent authorities in the state of Qatar will hold all those (who) committed (this) accountable,” Sheikh Saif said. The government later called the state TV footage “fake videos.” No group immediately claimed responsibility for the alleged hack.

Qatar has been targeted by hackers before, however. In May 2016, hackers leaked sensitive information involving thousands of Qatar National Bank customers, purportedly including government employees and members of the ruling family. In 2012, a damaging virus crippled computer systems at Qatari natural gas producer RasGas soon after a similar attack on Saudi Arabia's state-run oil company.

Amid Qatar's denials, Saudi-owned satellite television networks immediately began airing repeated stories about the disputed comments. By early Wednesday morning, internet users in Saudi Arabia and the United Arab Emirates could not access websites run by Al-Jazeera, based in the Qatari capital, Doha.

On Thursday morning, Bahrain and Egypt also apparently had blocked Al-Jazeera websites, though authorities did not immediately acknowledge it. Egypt also blocked other websites as well, including that of Mada Masr, a popular online news outlet known for its investigative reports on the Egyptian government.

Al-Jazeera said Wednesday it was “studying the reports our channels and digital platforms have been blocked in certain countries in the region.” It declined to comment further.

Qatar, home to the forward headquarters of the US military's Central Command and some 10,000 American troops, long has faced criticism from its Arab neighbors over its support of Islamists. The chief worry among them is the Muslim Brotherhood, a Sunni Islamist political group outlawed by both Saudi Arabia and the UAE as it challenges the nations' hereditary rule.

Gulf countries led by Saudi Arabia fell out with Qatar over its backing of then-Egyptian President Mohammed Morsi, a Brotherhood member. In March 2014, Saudi Arabia, the United Arab Emirates and Bahrain recalled their ambassadors from Qatar over the rift. Eight months later, they returned their ambassadors as Qatar forced some Brotherhood members to leave the country and quieted others.

In the time since, Qatar repeatedly and strongly denied it funds extremist groups. However, it remains a key financial patron of the Hamas-controlled Gaza Strip and has been the home of exiled Hamas official Khaled Mashaal since 2012. Western officials also have accused Qatar of allowing or even encouraging funding of Sunni extremists like al-Qaida's branch in Syria, once known as the Nusra Front.

As US President Donald Trump arrived in Saudi Arabia this week, Qatar issued a statement decrying “an orchestrated barrage of opinion pieces by anti-Qatar organisations” criticising it. One of those pieces, suggesting Qatar in 2006 may have let go a Qatari man who became an al-Qaida leader in Afghanistan, came from David A. Weinberg, a senior fellow at the Washington-based Foundation for the Defense of Democracies.

“The swift Saudi-Emirati response makes me think they were fishing for a confrontation or this is a convenient pretence ... to address the things already bothering them,” Weinberg said. “Qatar likes to write this off as a campaign based on lies and ulterior motives, but if Qatar didn't has the sort of problematic record it has, it wouldn't be the target for this.”