The United Nations and human rights groups are expressing concern over the arrests in Congo of 18 anti-government protesters in the eastern city of Goma.

The demonstrators with the Struggle for Change group were detained Tuesday when they marched to call for the release of two fellow members who were jailed a year ago.

A spokesman for U.N. Secretary-General Ban Ki-moon noted growing restrictions on Congo's democratic space and called on authorities to respect the right to freedom of expression, association and peaceful assembly as provided in Congo's constitution.

Amnesty International also criticized the arrests, saying they are evidence of further repression and human rights violations ahead of Congo's elections later this year.