BRUSSELS (Reuters) - The United Nations should consider a force of some 20,000 soldiers from non-NATO countries and 4,000 police to help resolve the crisis in Ukraine, according to a new report to be presented to top officials this week.

More than 10,000 people have been killed since April 2014 in a conflict that pits Ukrainian forces against Russian-backed separatists in eastern Ukraine. Intermittent clashes continue despite a notional ceasefire and diplomatic peace efforts.

Russian President Vladimir Putin has suggested a limited U.N. peacekeeping mission to eastern Ukraine, which many in the West see as an opportunity to negotiate a broader U.N. force to restore order, diplomats say.

A report commissioned by former NATO chief Anders Fogh Rasmussen - now an adviser to Ukraine’s President Petro Poroshenko - will be presented to officials including the U.S. special envoy to Ukraine, Kurt Volker, at the Munich Security Conference on Saturday.

“The operation would need a mix of some European countries, such as Sweden, countries with a track record in peacekeeping, such as Brazil, and countries that have Russia’s trust, such as Belarus,” said Richard Gowan, author of the report and an expert on the United Nations at Columbia University.

While numbers as high as 50,000 personnel have been mentioned by some diplomats and experts, Gowan said it was unrealistic to expect countries to put forward so many troops, while Moscow would likely resist such a large force.

Senior officials from Russia, Ukraine, Germany and France will discuss the conflict on the sidelines of the Munich Security Conference.

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Gowan said establishing a peacekeeping force could allow local elections to take place in eastern Ukraine - a key part of the 2015 Minsk peace accords negotiated by Kiev, Moscow, Paris and Berlin. They seek to restore Ukraine’s control over its border with Russia and withdraw heavy weapons from the area.

“If you were able to get a significant presence on the ground reasonably quickly, you would want to move toward local elections within 12 months, and then keep peacekeepers there for a cooling-off period, say two years in total,” Gowan said.

International police would also be crucial to establishing peace because soldiers in tanks would be ill-placed to deal with any protests that could follow such a vote, he said.

Over 700 unarmed civilian observers from the Organization for Security and Cooperation in Europe (OSCE) currently operate monitoring missions on the conflict, but these have not reduced tensions.

Difficult obstacles remain to the approval of any U.N. force. Russia, which has a veto as a permanent member of the U.N. Security Council, would have to agree to the details, and it is unclear whether Sweden would agree to lead the mission.