The Paris-based Reporters Without Borders said in a statement that Maikel Nabil Sanad, who began his hunger strike on August 23 and more recently started refusing to drink, "could very soon die."

"The Supreme Council of the Armed Forces would have to take full responsibility. Held for exercising his right to freedom of expression, Sanad must not become the symbol of a repressive and unjust post-Mubarak Egypt," it said.

A military court convicted Nabil in April on charges of insulting the armed forces, prompting US lawmakers to send a letter to the military ruler, Field Marshal Hussein Tantawi, demanding his release.

Nabil's trial was the first of a blogger since the military took charge of the country in February following president Hosni Mubarak's overthrow by a nationwide uprising.

The military, which has tried thousands of civilians since then, mostly for crimes such as theft and assault, faces growing pressure to refer civilian cases to normal courts. It has also jailed activists arrested in protests.

Opponents of military trials say they are unfair and result in harsh sentences.

Christian and Muslim groups claimed up to 42 people were killed Thursday in clashes in the central city, which has seen waves of ethnic and sectarian violence that left hundreds dead in recent years.

The head of a search and rescue team for the Muslim community claimed soldiers were responsible for most of the casualties on the Muslim side, which he said included 22 dead, as troops reciprocated after they were shot at.

An official from the Stefanos Foundation, a Christian group, said his side counted 20 dead and 50 wounded, mostly from machete cuts and gunshot wounds, but did not provide further details.

An AFP journalist saw 21 bodies in a mosque being prepared for burial.

"... The special task force is now mandated to use all the necessary force within its powers on anybody carrying and using arms and/or dangerous weapons on another person," Captain Charles Ekeocha said in a statement.

The military task force has been deployed to Jos over the repeated violence in the city and surrounding area.

Ekeocha's statement said three soldiers were shot and critically wounded.

The statement said it wanted to "make it clear to whoever is having the false confidence of trying their hands on the might of the Nigerian military to retrace their steps, as the special task force will bring her might to bear on any persons or groups of persons."

Jos lies in the Middle Belt region between the predominately Christian south and mainly Muslim north of Africa's most populous nation.