Eritrea's "systematic, widespread" human rights abuses should be referred to the International Criminal Court as crimes against humanity that include enslavement of up to 400,000 people, a United Nations commission of inquiry said Wednesday.

The commission said the government of the small Horn of Africa country has made no progress on most critical rights violations the group first documented a year ago.

Eritrean refugees are one of the largest groups trying to cross the Mediterranean Sea to Europe. The new report says 47,025 Eritreans applied for asylum in Europe in 2015.

Eritrean President Isaias Afwerki, in power since 1991, has become increasingly repressive, say rights groups.

"The crimes of enslavement, imprisonment, enforced disappearance, torture, persecution, rape, murder and other inhumane acts have been committed as part of a widespread, systematic campaign against the civilian population since 1991," commission chair Mike Smith told reporters.

The commission's role was investigative, not prosecutorial, Smith said, stopping short of identifying potential suspects or saying how many there are.

"Officials at the highest levels of state" bear responsibility for crimes against humanity, the report said, and the commission has compiled evidence for a number of officials that "will be made available at the appropriate time to relevant institutions, including courts of law."

Eritrea's government quickly shot back. A statement from presidential adviser Yemane Gebreab accused the panel of being "entirely one-sided."

The three-member U.N. commission, which was not allowed to visit Eritrea, said many violations occur behind "the facade of calm and normality that is apparent to the occasional visitor to the country."

It highlighted the indefinite duration and abusive conditions of Eritrea's military service.

Smith estimated that between 300,000 and 400,000 people are enslaved, mostly through military conscription. Eritrea's population is about 6 million.