Christian Solidarity Worldwide (CSW) has learned that the men are obliged to report to the National Intelligence and Security Service (NISS) every day, since being detained, questioned and released by NISS agents earlier in March.
Revd Ayub Tilyab, an SCC minister and President of the SCC National Council, and Revd Yagoub Naway, a minister from the SCC in Ombadda and Vice President of the SCC Ombadda Area Council, were arrested on 21 March by NISS agents and held for questioning.
The pair were later released without charge - on the condition that they report to the NISS office each day.
Another church member Benjamin Breama was also arrested by NISS in mid-March and released on the same day without charge.
These incidents are the latest in a series of arrests of religious leaders by NISS agents over the last few months.
In March another two reverands were arrested and released the same day. NISS agents confiscated their personal property, including laptop computers and mobile phones. Both men are required to report to the NISS offices daily.
The pattern of arrests began in December 2015, when a Christian activist and member of the Khartoum Bahri Evangelical Church, Talahon Nigosi Kassa Ratta was arrested.
He was detained without charge until the end of December at the Kober Men's Prison, but was later transferred to an unknown location.
CSW has reported that his family's visitation rights have been denied.
Christian Solidarity Worldwide's Chief Executive Mervyn Thomas said: "We are deeply concerned by the pattern of arrests and detentions of religious leaders and church members.
"Reverends Naway, Abraha, Hassan, Tilyab and Shamal and Mr Breama have not been charged with any crime, yet are required to report to NISS offices daily, which exemplifies the significant and continuing harassment of Christian minorities in Sudan.
"Their daily detention at the NISS offices, which is reported to extend at times from 8am to midnight, is an unjustifiable deprivation of their liberty and is tantamount to arbitrary detention in violation of Article 9:1 of the International Covenant on Civil and Political Rights (ICPR), which Sudan has bot signed and ratified.
"Furthermore, the impact of these daily detentions on the clergymen's religious duties amounts to a de facto interference in their right to freedom of religion or belief under article 18 of the ICCPR. We call on the Sudanese authorities to lift the daily reporting conditions placed on Reverends Naway, Abraha, Hassan, Tilyab and Shamal and Mr Breama.
"Furthermore we call for the immediate and unconditional release of Reverend Abduraheem and Mr Ratta. Their detention for over three months without charge, and without regular access to their families or a legal representative amounts to arbitrary detention and violates the principles of fair trial as articulated in article 14:3 of the ICCPR."
