A Sudanese judge has sentenced two senior members of a Darfur rebel group and six others to death by hanging for their role in an attack on the Sudanese capital in May.

The eight include Abdel Aziz el-Nur, a senior commander of the rebel Justice and Equality Movement (JEM) and the half-brother of the group's leader.

The accused shouted "Death to the government," as the verdicts were read.  They have one week to make an appeal before President Omar Hassan al-Bashir signs the execution orders.

Defense lawyers for the rebels argue that special courts set up to try alleged rebels are unconstitutional.

Sunday's ruling raises the number of people sentenced to death in connection with the May 10 attack on Khartoum, and its twin city of Omdurman to 38.  More than 200 people were killed in the fighting.

Sudanese President Omar al-Bashir has pardoned about 90 juveniles arrested by the authorities following the JEM attack. 

In a separate development, the United Nations says Ethiopian troops are joining the U.N.-African Union peacekeeping force in the Darfur region.   The first group of troops was scheduled to arrive in the North Darfur capital of el-Fasher on Saturday.

The U.N. says the contingent will be deployed to Kulbus and Silea in West Darfur where they will install water systems and electric power lines.

The U.N.-African Union force in Darfur currently includes about 10,000 soldiers and police - less than half of the number originally envisioned.

Darfur rebels began an uprising against the Sudanese government in 2003.  United Nations official say the fighting has killed as many as 300,000 people and displaced 2.5 million others. 

Some information for this report was provided by AFP, AP and Reuters.