A Nigerian Muslim nurse has been fired for defying a hospital dress code in the northern town of Zaria.  Muslim groups say her dismissal was unfair and violates her constitutional rights.

The Ahmadu Bello University Teaching Hospital, one of the largest health facilities in northern Nigeria, says the sacked nurse, Safiya Ahmed, persistently violated the dress code for nurses at the hospital.

The hospital says Safiya chose to wear "a different and unapproved hijab" in contravention of the existing dress code, which permits only shoulder-length hijab - the traditional head covering for Muslim women.

Safiya said she felt compelled to wear her hijab the way she did because of her religion. Several Muslim groups, including the Muslim Students Society of Nigeria, of which Safiya's husband is a member, are calling for her immediate reinstatement.  The head of the group, Nurudin Asunugle, accused hospital authorities of violating Safiya's constitutional rights.

"What has happened is a clear denial even of one's constitutional right to worship the way he worships. What is amazing is the fact that even the Nursing and Midwifery Council allows that ladies should be dressed the way she was dressed," said Asunugle.

Nigeria's 140 million people are split almost equally between Muslims and Christians and the two communities generally live peacefully side by side. But ethnic and religious tensions run deep.

The hijab controversy comes on the back of recent clashes between Muslims and Christians in parts of northern Nigeria.

Asunugle says his group will use any means possible, including violence, to get the sacked nurse reinstated.

"If violence is the only viable option, we do not rule that out," said Asunugle.

Many Muslim women in the predominantly Muslim northern Nigeria wear a hijab or head scarf. A significant number also wear the full-length veil through which only a woman's eyes can be seen.

The Ahmadu Bello Teaching Hospital is owned by the secular federal government, which has a more liberal approach to religion.