Ukraine says it has placed a formal request with the United Nations for a peacekeeping mission to be deployed in its eastern regions, where a cease-fire between government and Russian-backed separatist forces is in place.

Foreign Ministry spokesman Yevhen Perebiynis said Friday that the size and scope of the proposed mission would be worked out in consultation with the U.N.

A mission would need backing from all five permanent members of the Security Council, however, and Russia is likely to resist the move.

Perebiynis says the preliminary request for the mission has been submitted to U.N. Secretary-General Ban Ki-moon and that another would follow after Ukraine's parliament approves the proposal.

More than 6,000 people have been killed in east Ukraine since unrest flared up in April.