HELSINKI (Reuters) - Finland supports a proposed U.N. peacekeeping mission in eastern Ukraine but sees problems in narrowing down participants to only selected European Union countries, Defence Minister Jussi Niinisto said on Tuesday.

A report commissioned by former NATO chief Anders Fogh Rasmussen, now an adviser to Ukraine’s President Petro Poroshenko, proposed earlier this month that the United Nations consider a force of about 20,000 soldiers from non-NATO countries to help resolve the crisis in Ukraine.

The report listed non-NATO EU countries like Finland, Sweden and Austria taking key roles, along with NATO-countries perceived as friendly by Russia, such as Greece.

“Ideas of labeling some European Union countries as more acceptable than others should be rejected, Niinisto said.

“Also the composition of any possible peacekeeping operation should be broad-based and take into account operational requirements,” Niinisto said at a news conference in Helsinki with his Ukrainian counterpart Stepan Poltorak.

Poltorak was in Helsinki to discuss security in Ukraine with Niinisto and Finland’s president.

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.

Sweden, which was suggested as a possible lead nation for a U.N. force in the Rasmussen report, has said it would be open to providing troops to a peacekeeping mission.

Niinisto said the operation would need approval from both Russia and Ukraine, and gave no comment on how many troops Finland would be ready to provide.

“When it comes to number of troops, it’s too early to say anything ... but Finland, Sweden, Austria, Switzerland and Ireland cannot put up all the troops needed for this kind of operation. We need more countries”.