Information and media project Kubatana.net says its bulk messaging service has been blocked by the country's telecommunications regulatory body.
Kubatana, which uses various media tools to enable Zimbabweans to access and share information, discovered that they had been blocked Wednesday, when text messages kept bouncing back.
Amanda Atwood, the project's content manager, said when she contacted their mobile service provider Econet, she was told the Posts and Telecommunications Regulatory Authority of Zimbabwe (POTRAZ) had issued the directive to block the messages.
Speaking to SW Radio Africa, Atwood said: "On Wednesday when we noticed that our messages were not going through we contacted our international carrier who told us that our upstream (local) carrier Econet, was blocking us as a sender.
"We have been sending out bulk text messages to thousands of our opt-in subscribers for several years now without any problems.
"When I phoned Econet, someone in the business development unit said they had received a directive from their regulator POTRAZ to block all bulk messages coming from international gateways. Econet said we were being blocked for political reasons," said Atwood.
However when she asked to see the directive, she was told that the instruction had not been 'communicated formally'.
Coming less than a week before the country's watershed election, many will see the timing of the ban as an attempt by the ZANU PF controlled regulator to censor the kind of information Zimbabweans receive during this crucial period.
Kubatana said they will be approaching the Communications Ministry over the ban, which they described as "unconstitutional, obstructive, repressive and hostile.
"It is our opinion that as we approach the July poll the Zimbabwean authorities are increasing their control of the media, making the conditions for this election unfree and unfair," Kubatana further stated.
When SW Radio Africa contacted Econet, this reporter was transferred back and forth six times to departments including business development, the legal team, and public relations, but still could not get a comment.
A POTRAZ switchboard operator transferred us to three different officials before we were told to call back later.
Media watchdog Media Institute of Southern Africa (MISA) issued a statement Friday, expressing concern at what it described as an 'arbitrary' move by POTRAZ.
"MISA expresses concern about this alleged arbitrary move by POTRAZ which it deems retrogressive in light of the provisions of the new constitution which clearly states that every person has the right to freedom of expression which includes 'freedom to seek, receive and communicate ideas and information'.
"MISA-Zimbabwe is further concerned by the timing of this alleged 'ban' when the country is going through this critical transition phase which in itself needs diverse avenues for access to information and calls upon POTRAZ to reconsider the move," the statement stated.
On a number of occasions the government has tried to block or jam any messages perceived as hostile towards ZANU PF. In 2009, mobile phone network operators were directed to warn their subscribers not to disseminate political messages. This followed the mass circulation of text messages castigating ZANU-PF during the party's congress in December that year.
In 2010, following a Herald newspaper article threatening to withdraw Econet's licence, the company asked the MDC party to stop using its network for political purposes. Econet then announced that it was installing software to block political messages.
Also in 2010, the Broadcasting Authority of Zimbabwe tried to block Kubatana Freedom Fone's Interactive Voice Response service, arguing that the service was a form of broadcasting, and that Econet was facilitating unlicensed broadcasting.
Although both Econet and Kubatana won the matter in court, that was not before Econet had disconnected the service, pending investigations by its legal department.