An Upper Islamic Sharia court in the northern city of Kano on Monday ordered 22-year-old Yahaya Aminu Sharif to die by hanging for derogatory expressions against the Prophet in one of his songs.

“This is a travesty of justice. There are serious concerns about the fairness of his trial; and the framing of the charges against him based on his music,” Osai Ojigho, Nigeria director of Amnesty International, said in a statement.

“Furthermore the imposition of the death penalty following an unfair trial violates the right to life. Yahaya Sharif-Aminu must be released immediately and unconditionally,” Ojigho added.

Amnesty said the death penalty “violates Nigeria’s obligations under the International Covenant on Civil and Political Rights which restricts the use of the death penalty to crimes like intentional killing, according to international law.”

Sharif was accused of blaspheming the Prophet in a song he shared on social media in March, which caused riots in the city.

Mobs burnt the singer’s family home and took to the streets demanding his prosecution, leading to his arrest.

Sharif had legal representation during the four-month trial which was held behind closed doors for security reasons.

Sharif belongs to a branch of Sufism, the Tijaniyya order, whose beliefs are considered heretical to mainstream Muslims because of their different interpretation of some basic Islamic principles.

His conviction is the second death sentence to be passed for blasphemy since around a dozen states in the north reintroduced a stricter version of Sharia law in early 2000s, where Sharia courts run parallel to state and federal justice

The musician has one month to appeal the conviction.

Although sharia courts have handed down death sentences for adultery, rape, murder and homosexuality in the past, no executions have been carried out.