Eritrean operations in east Sudan?

An Eritrean opposition party official has been missing for two days in eastern Sudan and there are fears he may have been kidnapped by Asmara's security agents, the party alleged on Thursday.
Mohammed Ali Ibrahim, a member of the People's Democratic Party central council, left his house in Kassala town at 8:00 am (0500 GMT) on Tuesday and has not been seen since, the party said in a statement emailed to AFP.

Sudanese police and the Kassala hospitals had no word on him, it said. "The big fear prevailing in Kassala is that he might have been kidnapped by security agents of the Eritrean regime, who enjoy free mobility in the region," it said.

Eastern Sudan is home to tens of thousands of ethnic Eritreans.

The United Nations refugee agency in Sudan says about 2,000 asylum-seekers, mostly Eritrean, cross the border monthly, many to escape the Asmara regime's compulsory military service.

There are around 80,000 people living in refugee camps near the border, some of whom began fleeing to Sudan four decades ago during their country's independence war with Ethiopia.

AFP, via Harnet.org
For further analysis, try this article from the Christian Science Monitor.

An additional article published in the Sudan Tribune says:

Many Eritrean opposition parties are based in neighbouring Sudan and Ethiopia, where thousands of refugees have fled following forced military national service and a lack of political and religious freedom.
The office of the United Nations Refugee Agency (UNHCR) in Kassala has been informed, the EPDP say, as well as UNHCR’s headquarters in Geneva and the International Committee of the Red Cross (ICRC).
The group accused the Sudanese government of collaboration with the Eritrean officials and intelligence services in handing over opposition officials and other refugees who fled home in protest to oppression by regime in Asmara.
According to the Eritrean opposition group, Khartoum does not allow Eritrean opposition groups to operate in its territory as part security agreements between the two east African neighbours.
EPDP condemned the acts by the Sudanese government and called on the international community to intervene over the situation.