(Adds more Sikorski quotes, paragraphs 15-16, 20)

By Gareth Jones

WARSAW, Sept 11 (Reuters) - Russia's foreign minister told Poland on Thursday a U.S. missile defence shield Warsaw has agreed to host poses a direct threat to his country's security, but said Moscow remains open to further talks.

Poland has infuriated Moscow, its former communist-era overlord, by agreeing to host 10 interceptor missiles as part of the missile shield project. Washington says the shield is aimed against what it calls "rogue states" like Iran, not Russia.

"We cannot fail to see the risks emerging as a result of U.S. strategic forces coming closer to our borders," Foreign Minister Sergei Lavrov told a joint news conference with his Polish counterpart Radoslaw Sikorski.

"We are certain this system in Europe can have no other target for a long time to come but Russia's strategic forces."

Russia's Prime Minister Vladimir Putin warned the West on Thursday against starting an arms race in Europe by stationing a U.S. missile defence shield near Russia's borders and said there was no basis for a new Cold War.

Putin also warned Poland and the Czech Republic against hosting the U.S. missile shield.

"Our targeting of these countries will happen as soon as these missiles are brought," Putin said. "Please do not instigate an arms race in Europe. It is not needed. What should we do? Sit pretty while they deploy missiles?"

But Lavrov, on his first trip to a European country since last month's Georgia crisis reignited tensions between Russia and the West, balanced his comments with a call for dialogue.

"We don't see Poland itself as a source of threats to the Russian Federation ... We don't agree on everything but we appreciate dialogue," he said.

GUARANTEES URGED

In an interview for the Polish daily Gazeta Wyborcza published on Thursday, Lavrov urged the United States and its allies to provide guarantees to Moscow that the shield would not be targeted against Russia.

His comments in Poland marked a slight softening of Russia's position after President Dmitry Medvedev recently said Moscow would have to respond militarily to Warsaw's shield decision.

Sikorski stressed the need for confidence-building measures and also reiterated Polish and U.S. arguments that the shield, which will also include a radar installation in the Czech Republic, s no match for Russia's vast nuclear arsenal.

A senior aide to Polish Prime Minister Donald Tusk hailed the change of tone, saying it could bring concrete results.

"Both sides are ready to talk about how to build trust ... This means that both sides are willing to talk also about inspections of each other's military bases," aide Slawomir Novak told reporters in televised remarks.

Pressed on the issue of inspections in a television interview, Sikorski said reciprocity was key.

"We will propose a mutual formula in which inspections, but not a permanent stationing, will ensure the (U.S. shield) base serves only the purposes we have declared," he told Polish TV.

Polish officials and political analysts have expressed surprise that Lavrov pressed ahead with his long-scheduled trip to Warsaw despite the missile shield row and Poland's vocal support for Georgia during the South Ossetia crisis.

They say it underscores Russia's wish to repair ties with Europe after Moscow found itself largely isolated globally over Georgia. Poland, the largest ex-communist member of NATO and the European Union, is an important trade partner for Russia.

Russia provides some 95 percent of Poland's oil and nearly half of its natural gas. Bilateral trade totals $18 billion.

"In such tense international circumstances the fact this visit has taken place and that we are continuing with growing trade relations between our countries is a positive factor," Sikorski told TVN 24.

Lavrov reaffirmed Moscow's opposition to NATO expansion, a cause long championed by Poland which especially wants its big eastern neighbour Ukraine and Georgia in the Atlantic alliance.

Sikorski said free, democratic countries should decide for themselves whether they wanted to join NATO.

(Additional reporting by Gabriela Baczynska in Warsaw)

(Writing by Gareth Jones; editing by Robert Hart)

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