The YouTube video shows an unidentified woman in a long black dress and a headscarf being ordered to sit down in a parking lot (Warning:Video contains graphic images of violence some may find disturbing).
A uniformed policeman proceeds to whip her all over her body as she screams in pain. A second officer laughs when he realises he is being filmed, before joining in the punishment, which lasts a minute and a half.
Flogging is relatively common is northern Sudan, where sharia law is often enforced arbitrarily. But the cruel, nonchalant behaviour of the security forces amid the distress of the victim in this case caused a stir in the country and the diaspora, and even attracted condemnation in some pro-government newspapers.
Initially Sudan's deputy police chief, Adel Al-Agib, tried to downplay the incident, saying that the footage was circulated in order to damage the image of the country, according to the Sudan Tribune newspaper.
But the judicial authority, which oversees the legal system, released a statement yesterday saying it had launched an official inquiry to see if the punishment had been administered improperly.
"The investigation was started immediately after the images of the young woman, being punished under Articles 154 and 155 of the 1991 Sudanese penal code, appeared on the internet," the judiciary said in a statement, according to state media.
These articles allow up to 100 lashes for adultery and running a brothel, in addition to a jail sentence. In this case the woman's alleged crime is not known, although comments on social media sites suggest it could have been the wearing of trousers, which has in the past been judged to violate a law governing "indecent or immoral dress".
In the subtitles on the clip, a policeman can be heard telling the women that her punishment is 53 lashes, and that she will be jailed for two years if she does not submit to the flogging. Another voice says the woman should comply because "we want to go [home]".
During her ordeal, which was witnessed by numerous passers-by, the victim shouts repeatedly for her mother and grabs one the whips of one of the policeman in a vain attempt to stop the beating. The case follows the well-publicised trial last year of Lubna Hussein, a UN worker who was arrested with a dozen other women for wearing trousers at a party in the Sudanese capital, Khartoum.
While most of the women accepted the punishment of 10 lashes, she refused, challenging the verdict in court. Ultimately found guilty, she was given a fine rather than being whipped.
Though less frequently, men have also fallen foul of the laws on dress. Last week a Khartoum court convicted seven men of indecency for wearing make-up. The defendants, all amateur models appearing at the "Sudanese Next Top Model fashion show", were fined 200 Sudanese pounds (£54) each. The Guardian
