(U.S. officials say Warsaw stop unlikely)

By Sue Pleming

WASHINGTON, July 7 (Reuters) - Polish Foreign Minister Radoslaw Sikorski met U.S. Secretary of State Condoleezza Rice on Monday to salvage negotiations on a missile defense system opposed by Russia, but there was no early sign of a deal.

The talks were "productive" but negotiations would continue, Sikorski said after his meeting with Rice at the U.S. State Department, indicating there had not been a breakthrough.

"As regards missile defense, we have clarified our positions and we have had some productive ideas. The talks continue," Sikorski told reporters, without providing details.

State Department spokesman Sean McCormack was noncommittal over whether a deal was close. The talks were held hours before Rice was due to leave on a trip to Europe that could include a stop in Poland if a deal could be reached in time.

"We haven't completed them yet. And we're still working on them. The fact that the Polish foreign minister is here today is evidence of the fact that we are continuing to work on these negotiations," McCormack told reporters after the talks.

"We did not conclude them in time for the beginning of the secretary's travel, but that does not mean we are not going to keep working on it. It is an important issue for Poland and it is an important issue for the United States," he added.

U.S. officials said if a deal was reached in the next few days, they thought it highly unlikely that Rice would add a stop in Warsaw this week to sign it.

So far, Poland has rejected as insufficient a U.S. proposal to upgrade Poland's armed forces.

The United States wants to base 10 missile interceptors in NATO ally Poland as part of a drive to counter perceived threats from what Washington calls "rogue states," particularly Iran.

AIR DEFENSES

In return, Poland has sought billions of dollars in U.S. investment to upgrade its air defenses, including Patriot ground-to-air missiles. Last Friday, the government spurned a U.S. offer but said it was open to more talks.

"I think we've got a signal from the American side that they are ready to negotiate," Polish Foreign Ministry spokesman Piotr Paszkowski told TVN 24 in Warsaw.

Rice leaves for Prague later on Monday to sign a treaty to build a tracking radar on Czech soil as part of the missile defense plan. The treaty still has to be ratified by the Czech parliament, where it faces some opposition.

If Rice and Sikorski had clinched a deal on the Polish interceptors, diplomats said Rice could visit Warsaw at the end of her European trip, probably on Thursday.

"We are preparing for the visit (of Rice) as if it were to take place," Paszkowski said.

McCormack did not completely rule out Rice visiting Poland while on her trip to Europe, but such a stop was less likely after the meeting in Washington did not produce a breakthrough.

"If she thinks it's useful, diplomatically, to make a stop somewhere then of course she will," McCormack said. "I just don't do timelines on negotiations," he said when pressed whether he thought the deal could still be sealed in time for Rice to visit Poland this week.

The full details of the U.S. offer to Poland have not been made public but Polish Prime Minister Donald Tusk said on Friday it included putting Patriot batteries on Polish soil for one year, a proposal he said did not go far enough.

Russia has condemned the U.S. missile defense plan as a threat to its own security and has threatened to target missiles at Poland and the Czech Republic -- its communist-era satellite states -- if the deployment goes ahead. (Additional reporting by Gareth Jones in Warsaw; Writing by Sue Pleming; Editing by Eric Beech and )

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