On Sunday, Czech Christian aid worker Jasek was found guilty of espionage and sentenced to life imprisonment. A life sentence in Sudan lasts 20 years.
Jasek also received a further three years imprisionment and a fine of US$15,000 for entering military areas; inciting hatred between sects; propagation of false news; entering the country illegally; and violating Articles 8 and 23 of Sudan's Volunteer Act.
Rev Abduraheem and political activist Abdumawla were sentenced to ten years for espionage and a further two years for inciting hatred between sects and spreading false news.
Lawyers intend to appeal the verdict and sentencing. The men, who have already been in jail for over a year, have been returned to their cells in Al-Huda prison in Omdurman.
The case against the three men centres on the provision of $5000 for the medical treatment of Mr Ali Omer, a Darfuri student who was severely injured during a student demonstration.
Christian Solidarity Worldwide's Chief Executive Mervyn Thomas said: "We are profoundly dismayed by this verdict. The serious charges against these men were wholly unwarranted, and the excessive sentences are unjustified, given the paucity of evidence against them.
"Mr Jasek, Reverend Abduraheem and Mr Abdumawla are not spies; they were simply driven by compassion to source finance for the medical treatment of a man whose injuries are so severe that he requires ongoing medical care. We call for the annulment of the verdict and the immediate release of these three men.
"In addition we urge the Sudanese authorities once again to undertake a review of the sweeping powers exercised by the NISS, and to end the targeting of ethnic and religious minorities."
Sarah - the Africa advocacy officer from anti-persecution charity Christian Solidarity Worldwide - told Premier's News Hour it could have been worse.
She said: "The maximum sentence for that could have been the death penalty and whilst we're thankful that the death sentence has not been passed, it's a very serious sentence when these men have committed no crime."
Listen to Aaron James speak to Christian Solidarity Worldwide here: