Yousef Nadarkhani, Mohammadreza Omidi, Yasser Mossayebzadeh and Saheb Fadaie were told that their 10-year sentences received on 6 July 2017 would remain unchanged.
However, Nadarkhani and Omidi have also been sentenced to two years internal exile in areas far away from their families.
Mossayebzadeh, Fadaie and Omidi faced separate charges for the consumption of wine as they were taking communion at the time of their arrest, and were sentenced to 80 lashes each in 2016.
Their appeal against this sentence remains outstanding.
On 13 December 2017 all four defendants attended an appeal hearing at the Revolutionary Court in Tehran in front of two judges.
Christian charity Middle East Concern has urged Christians to pray for "the Lord to comfort and encourage the four men and their families" and to pray "it will not be necessary for the four men to serve such harsh sentences".
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