Four people suspected of being Islamic State supporters arrested in anti-terrorism police raids across Johannesburg are expected to appear in court in Monday.

The four‚ a woman and three men aged between 20 and 24‚ were arrested in raids on homes in Newclare and Azaadville on Sunday .

The arrests bring to an end a year-long investigation by the Hawks and the State Security Agency.

Hawks spokesman Brigadier Hangwani Mulaudzi said the police seized ammunition and stun grenades.

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Asked about plans by the four to fly to Syria by way of Turkey last year to join IS‚ Mulaudzi said that the investigation was at a “highly sensitive stage“.

“[But] we can confirm that the four were prevented from leaving the country last year.

“We are investigating numerous allegations‚ including that they were going to join the IS group.

“We infiltrated the group after receiving information on them and their plans.

“We are not at liberty to say what those plans were‚” Mulaudzi said.

He said the police also seized electronic devices‚ including computer hard drives‚ and documents in the raids.

“The electronic items have been sent for analysis.”

Mulaudzi said the Hawks were investigating allegations that the four were involved in recruiting extremists.

He said the operation coincided with other anti-terrorism operations under way across the country — TMG Digital/The Times