Poland's painful memories of Soviet and Nazi occupation in World War 2 has made it wary of rushing into a deal to host a US missile shield site, Polish Prime Minister Donald Tusk has said.

Tusk meets President George W Bush on Monday to talk about the shield, which the United States says will protect it and its allies from ballistic missiles that could be fired by Iran or other "rogue" states.

US diplomats had hoped a preliminary agreement on the European missile shield could be reached before the project is discussed at a Nato summit in Bucharest in April. But Tusk said talks could take longer.