By Robin Emmott and Alastair Macdonald

BRUSSELS (Reuters) - Ukraine sought political support from NATO on Monday as talks with Russia in Brussels failed to bridge differences over a trade deal at the heart of east-west tensions and Kiev said Moscow was threatening a trade embargo against it.

In a day of meetings with EU and NATO officials, Ukraine's foreign minister said the secretary general of the U.S-led NATO alliance would make his first visit to Ukraine this month, dismissing concerns it could worsen tensions with Moscow.

Pavlo Klimkin, who called Jens Stoltenberg's visit symbolic as his ex-Soviet nation seeks to integrate with the West, also held talks with the EU's trade chief and Russia's Economy Minister Alexei Ulyukayev, but to little avail.

Ulyukayev said chances were slim of persuading Moscow that a free-trade deal between Ukraine and the European Union, which is due to come into force in January, would not be detrimental to the Russian economy.

Asked whether a deal to satisfy Moscow's objections to the deal could be reached before Russia imposed an embargo, Ulyukayev said work was progressing with difficulty.

"But we believe our combined efforts can succeed in achieving the result we want. There is a chance of that, although I wouldn't say it's very great."

The deal is at the heart of tensions that have grown from a tug-of-war over influence in Kiev to sanctions, the annexation of Crimea by Russia, armed conflict in eastern Ukraine, and concern among some in the West about a new Cold War.

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The start date for the trade deal is already a year later than planned as Russia seeks to oppose European efforts to integrate Ukraine and move it out of Moscow's orbit. Russia is pushing for the deal to be postponed by at least another year.

Asked if Russia was considering the same sanctions against Ukraine as it has applied to the European Union, he replied: "In principle, the same."

Moscow has banned the import of food from the EU in retaliation for EU sanctions imposed over Russia's annexation of Crimea from Ukraine.

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Both Ukraine and NATO say they have overwhelming evidence Russia has provided men and weaponry to the rebels in eastern Ukraine, but Moscow denies providing anything other than political support.

Stoltenberg is expected to inaugurate NATO-Ukrainian civil protection exercises at a time when the deadline is nearing for fulfillment of a peace agreement that has so far failed to stop low-level fighting in eastern Ukraine.

Ukraine dropped its bid to join the 28-nation U.S.-led Atlantic alliance in 2010 to please Moscow, but has now again set its sights on joining, seeing NATO membership as the only way to protect its territory.

(Reporting by Robin Emmott; editing by Ralph Boulton)