Egypt has blocked Avaaz campaigning site in the latest clampdown on websites by Cairo authorities

US-based civic organisation Avaaz has joined more than 60 websites and service providers blocked by Egyptian authorities since the end of May, a rights group has said.

Back in May, around 20 websites based in Qatar and in Egypt were made inaccessible, including the Al-Jazeera and the independent Egyptian news site Mada Masr, which has been critical of corruption in the country.

By Tuesday, the number of blocked sites had risen to 64, the Association for Freedom of Thought and Expression (AFTE) said on its website.

They included 10 Egyptian news websites as well as several Virtual Private Networks (VPN) providers that can be used to get around state-imposed censorship, it said.

Avaaz, a 44 million-member US-based civic organisation that promotes activism internationally, responded to the block by launching a petition addressed to Egyptian President Abdel Fattah al-Sisi demanding an end to "the information blockade".

"Before this censorship spreads, let's come together in massive numbers to show Sisi and other leaders across the Middle East that the world won't stand by when governments attack freedom of speech and human dignity," the petition read.

"We're not alone - this is part of a vicious crackdown on civil society across the country, with hundreds of activists being imprisoned and news outlets being shut down," it added.

"This is an attack on our whole movement, and the democratic freedoms it represents."

According to the website, Egypt is home to the largest community of "Avaazers" in the Middle East.

In April, Egyptian activists used Avaaz to call on the Egyptian authorities to pardon young detainee Ahmed al-Khatib, who had contracted visceral leishmaniosis in prison.

"We call on the Egyptian government to release Ahmed al‐Khatib so he can receive the appropriate treatment in an advanced hospital outside Egypt," read the petition, which has gathered over 36,000 signatures so far.

Before this censorship spreads, let's come together in massive numbers to show Sisi and other leaders across the Middle East that the world won't stand by when governments attack freedom of speech and human dignity. - Avaaz

The latest Egyptian news websites made inaccessible also include al-Badil and al-Bedaya, which has often published material critical of government policies.

Al-Bedaya's chief editor, Khaled al-Balshy, told AFP he had submitted a complaint to the Egyptian journalists' union, demanding to know why his website was blocked and by which state authority.

The government has yet to comment on the crackdown.

Hatem Zakaria, secretary general of the journalists' union, told AFP that this and another media organisation were planning to lodge a formal request seeking an explanation as to why the sites were blocked.

Rights groups have repeatedly accused Sisi of stifling dissent.

On Tuesday, Amnesty International condemned Egypt's block on the websites.

"The latest clampdown on digital media is further evidence of Egypt's age-old police state tactics in motion," said Najia Bounaim, Amnesty International's North Africa campaigns director.

"Even in the darkest days of the repressive Mubarak-era the authorities didn't cut off access to all independent news sites."

The London-based watchdog added that with this move, Egyptian authorities seemed to be targeting "the few remaining spaces for free expression in the country".

"It shows just how determined the authorities are to prevent Egyptians from accessing independent reporting, analysis and opinion about Egypt," it said, urging the authorities to "immediately stop arbitrarily blocking news websites".

An anti-terrorism law, adopted in August 2015, lays down stiff penalties for publishing "false information" on attacks in Egypt that contradicts official reports from the defence ministry, stirring condemnation from rights groups.

In the 2017 press freedom index published by watchdog Reporters Without Borders, Egypt ranks 161st out of 180 countries.