Islamist rebels in eastern Syria have ordered women to put on the Islamic veil, warning that anyone not doing so would be held to account, Reuters reports.

According to the report, an organization calling itself the Islamic Law Council of Deir al-Zor said in a statement released Wednesday that women have until Saturday to don the face veil.

The group did not say what punishment would befall women who fail to comply with the order.

Armed Islamist groups have become the most powerful force in the almost three-year-old uprising against President Bashar Al-Assad.

“Given that sins are the main reason delaying victory, the legal council in the town of Deir al-Zor is obliged to promote virtue and prevent vice,” said the statement posted by an activist on Facebook and also reported by the Syrian Observatory for Human Rights.

The civil war in Syria has attracted rebel groups with links to Al-Qaeda, such as the Al-Nusra Front and the Islamic State of Iraq and the Levant (ISIS). In addition to fighting President Bashar Al-Assad’s forces, these groups have been fighting the more moderate rebel groups in what has turned into a second war.

These Al-Qaeda-linked groups have been heading to war-torn Syria from many other countries since fighting broke out in 2011.

In recent weeks, the infighting between rebels has worsened, as three powerful rebel alliances – among them Islamist groups – have teamed up to fight the Islamic State of Iraq and the Levant (ISIS), which they have warned is even worse than Assad’s regime.

ISIS has been accused of several human rights abuses, including torturing and murdering prisoners, among them children and teenagers, and forcing Druze men to convert to Islam or die.

Last month, the New York-based Human Rights Watch reported that ISIS and another jihadist group, Al-Nusra Front, were enforcing their strict interpretation of Islamic law by requiring women to wear head scarves and full-length robes.

Several months ago, ISIS members raided a wedding party in a suburb of Aleppo, which Islamist rebels have declared to be an independent Islamist state, and ordered that music and singing be stopped.

The groups’ leader reportedly asked the man in charge of the wedding to memorize a verse of the Quran and attend several religious courses at Al-Qaeda’s center in Maskana, near Aleppo.

Some of the Islamist groups have attempted to soften their image in an attempt to win hearts and minds – holding stand up comedy shows and handing out toys to local children.