Islamic State (Isis) has banned the use of WiFi outside of Internet cafes in their de facto capital of Raqqa, according to local activists.

Syria Is Being Slaughtered Silently (RSS), a citizen journalism blog exposing the atrocities of IS in the Syrian city, said internet access has been limited to public cafes.

The militants reportedly ordered Internet providers to block web services in homes, including those of IS fighters. Cafe owners have four days to report to IS on the matter or face punishment.

Since the start of US-led coalition airstrikes in August 2014, the jihadist group has scrambled to reduce leaks of their fighters' online activities. The Financial Times reported of an Arabic language manual distributed among fighters that gave detailed instructions on how to remove metadata from content published online.

Fighters have inadvertently revealed valuable information about their names and locations in tweets and pictures online. As a result, there was a drop in the numbers of fighters using social media.

In Raqqa, the group had become paranoid about the use of WiFi and the extension of internet coverage in the city after the region became target of US bombs.

The move is likely aimed at restraining Raqqa residents and activists who have been documenting the group's atrocities in Syria. Earlier in July, the jihadist group executed two young media activists in Raqqa in an alleged attempt to score a victory against RSS.

A video released by the jihadist group shows two activists in their early 20s, named as Bashar Abdul Atheem and Faisal Hasan al-Habib, wearing orange jumpsuits and being interrogated about their anti-IS activities, which supposedly include handing out leaflets criticising Sharia law.

The duo was forced to confess that they monitored the activities of IS and were paid $400 (£260) for taking pictures of oil wells around Raqqa province, according to IBTimes India. The footage ends with the two activists, who had been previously tied around their waists to a tree trunk, being shot dead by two IS militants wearing balaclavas and camouflage.

Abu Mohammed, a media activist for RSS, confirmed to IBTimes UK via Skype that the two activists were executed by IS, but denied the claim that they work with them.

"I don't know whether they are activists. Reports came out saying they were working with us, but that is not true. I'm surprised by these reports," Mohammed said.

He added IS was trying to score a victory against RSS "because they are not able to do anything with us".