UNITED NATIONS (Reuters) - Ukrainian President Petro Poroshenko dismissed a Russian proposal to deploy U.N. peacekeepers in eastern Ukraine as an effort to legalize its proxies and freeze the conflict.

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Relations between Kiev and Moscow have never been worse since Russia annexed Crimea more than three years ago and Russian-backed separatist fighters subsequently took up arms against Ukrainian government forces in the east of the country.

Russian President Vladimir Putin this month suggested armed U.N. peacekeepers be deployed to eastern Ukraine to help protect ceasefire monitors from the Organization for Security and Cooperation in Europe (OSCE) and to help end a conflict between Ukrainian troops and Russia-backed separatists, which has killed more than 10,000 people since 2014.

Poroshenko used his speech at the annual gathering of world leaders for the United Nations General Assembly to accuse Moscow of not contributing to international security, but of being its “biggest threat.”

“The latest hybrid peacekeeping proposal from Moscow is yet another example of Russia’s real ambition to legalize its proxies and freeze the conflict forever,” he said.

“We remain confident that a fully fledged peacekeeping operation is the only viable solution to de-escalate and protect the people of Ukraine.”

Putin originally said the peacekeepers should be deployed along the line of contact between Ukrainian government forces and pro-Russian separatists, but later said they could also be deployed in other areas where OSCE inspectors work.

“The peacekeepers’ mandate should cover the entire occupied area, including the Ukrainian-Russian state border. This is the must. As long as the border is used as the main supply route for manpower and weapons to Donbass there will be no peace in my country,” he said.

Kiev and Western countries accuse Russia of providing military backing to the insurgency in eastern Ukraine. Russia denies any direct role in the conflict.

Efforts to broker an end to fighting through the so-called Minsk agreements have so far failed. Violence continues with attempted ceasefires repeatedly broken. Western powers fear peace efforts could unravel.

“The key problem in Donbass is that Ukraine and Russia strive for different things,” Poroshenko said. “Ukraine wants peace and restoration of its sovereign territory, but Russia wants control of Ukraine and undermines every effort (to get) our sovereign control on Ukraine’s border.”

Ukraine’s alternative plan would ban any Russian nationals from taking part in a peacekeeping mission which it wants deployed along the part of its border with Russia which it does not control, an idea Moscow has so far balked at.