The women, thought to be between the ages of 18 and 23 were stopped by Public Order Police after leaving a celebration service at the El Izba Baptist Church in Khartoum, the capital.
According to Christian anti-persecution charity Christian Solidarity Worldwide (CSW), the women, who were wearing skirts and trousers, were taken to a police station and forced to remove their clothes, which were submitted as evidence to the prosecutor.
Two of them were released without charge.
But Ferdoos Eltoum, Hala Ibrahim, Ishraga James, Uthan Omer Eljaily, Diana Yagoub Abd Alrahman, Seema Ali Osman, Inas Mohamed Elkomani, Rehab Omer Kakoum, Nasra Omer Kakoum and Wegdan Aba Alla Salih were charged with indecent or immoral dress under the Sudanese Criminal Code.
The 10 women have been released on bail and are awaiting hearings.
Despite the police report recording the women as being aged 18 and over, there are suspicions that three of them may be under the age of 18.
There is broad scope to define what constitutes indecent or immoral dress.
Lawyers representing some of the women said: "Two of the women were released.
"Who decided that their dress was no longer immoral if when they were arrested their dress was considered indecent?
"The law needs to be clarified."
CSW's Chief Executive Mervyn Thomas said, "We are deeply concerned by the unwarranted arrest of these 12 young women and are alarmed by reports that three of them may be minors who have been arrested arbitrarily and charged as adults in violation of their rights under Articles 37 and 40 of the Convention on the Rights of the Child, to which Sudan is a party.
"Furthermore, forcing these young women to undress amounts to degrading treatment, as defined by Article 7 of the International Covenant on Civil and Political Rights, to which Sudan is also a party.
"We urge the Sudanese authorities to discontinue the cases against these young women and to clarify the law, ensuring consistency and equality before the law for all Sudanese citizens. In addition the arrests of Pastor Hafez and Mr Mustafa, who also face unwarranted charges, are a cause for great concern.
This unacceptable harassment of a human rights defender during the discharge of his duties may be an indication of high-level efforts to interfere with the judicial process in cases involving religious minorities by discouraging lawyers from offering assistance.
"Once again we appeal to the international community, in particular the African Union, to hold Sudan to its international obligations."
