(Adds comments from Rice)
By Arshad Mohammed and Jan Lopatka
PRAGUE, July 8 (Reuters) - U.S. Secretary of State Condoleezza Rice said talks with Poland on a European missile shield remained unresolved, hours before she was to sign a treaty with the Czech Republic on its part of the accord.
The Bush administration wants to build the radar part of the system southwest of the Czech capital despite public opposition in the central European NATO member and protests by Russia.
The radar would be part of a shield Washington says would defend it and its European allies against any missile attacks from foes such as Iran. Intelligence reports suggest Tehran could develop a missile capable of striking U.S. soil by 2015.
"This missile defence agreement is significant as a building block, not just for the security of the United States and of the Czech Republic, but for the security of NATO and ultimately for the security of the international community," Rice said.
She all but ruled out travelling to neighbouring Poland after meeting its foreign minister on Monday. Washington wants to put 10 interceptor rockets there, but talks have run into difficulties over Warsaw's demands for billions of dollars to modernise its army and air defences.
Rice said the talks had been constructive but would not predict whether the two sides would reach a deal.
"I believe strongly that we are at a place where these negotiations need to come to a conclusion," Rice told reporters. "We are going to have to see if we can close the remaining gap."
She said missile proliferation was "not an imaginary threat" and noted Iran continued to enrich uranium -- which could lead to a nuclear weapon -- despite international demands it stop.
"They also continue apace their missile development, and so we need to be prepared for that threat," Rice said.
BASES NEAR RUSSIA
Russia says the shield is a threat and it will aim nuclear missiles at central Europe if it is deployed. The United States says the 10 rockets are no match for Russia's atomic arsenal.
The United States was willing to make arrangements to make the system transparent to Moscow, but Russia would also have to discuss this directly with the Czech Republic, Rice said.
Analysts say the planned bases in the former Soviet bloc would raise U.S. security interests in the region at a time when Russia grows more assertive about its role on the global stage.
"Moscow, of course, sees the move as a provocation and as a long-term security threat, and will seek to extract a hefty geopolitical or strategic price for going along," said Alexandr Kliment, an analyst at political risk consultancy Eurasia Group.
Russian President Dmitry Medvedev said after meeting U.S. counterpart George W. Bush on Monday the two sides should keep talking despite failing to overcome differences on the shield.
The shield plan still faces hurdles, including widespread public opposition in the Czech Republic, which experienced two decades of occupation after the Soviet invasion of 1968.
It also faces obstacles to ratification in the Czech parliament, where the government has just 100 seats in the 200-seat chamber. Some backbenchers say they will oppose it.
The vote may come only after a new U.S. administration takes over from Bush in January.
An opinion poll last month showed 68 percent of Czechs were against the shield, while 24 percent supported it, and protests were planned later for Tuesday.
"We believe that this could start another arms race, and we believe this will not raise the security of the Czech Republic," said Frantisek Smrcka, who along with other protesters unfurled a huge banner shaped like a target in the Czech capital.
Rice will also travel to Bulgaria and Georgia on her European trip this week. (Reporting by Arshad Mohammed; Writing by Jan Lopatka and Michael Winfrey; Editing by Charles Dick)