The Polish government does not agree with U.S. plans to place a missile defense base in the country, TV channel TVN24 quoted a source close to the Foreign Ministry as saying, reported RIA Novosti
Prime Minister Donald Tusk was discussing the issue with the foreign and interior ministers, the channel said.
A special news conference on the missile shield that Tusk was scheduled to give at 3:00 p.m. local time (13:00 GMT) was postponed.
The prime minister said Poland objects to the terms offered by the U.S. for the deployment of a missile defense base on its soil, but is ready for further dialogue.
"We need firm guarantees from Washington that the deployment of a missile defense base will enhance Poland's security," he told reporters.
On Thursday evening Tusk discussed the issue with U.S. Vice President Dick Cheney, and the sides reportedly failed to overcome disagreements.
The discussion took place after Polish and U.S. officials said Wednesday that two-day talks in Washington had resulted in a tentative agreement on the deployment of 10 interceptor missiles in Poland.
The Polsat News channel said Warsaw is continuing to press ahead with its demands for greater funding on the modernization of its air defenses and compensation for possible accidents at the base.
The U.S. already gives Poland $27 million per year in military funding, the most any European ally receives, and the Bush administration earlier this year offered an extra $20 million per year.
Washington also wants to put a radar in the Czech Republic as part of its missile shield. The Czech government has agreed to the plan in general, but parliament still needs to approve the deal.
Russia fiercely opposes Washington's missile shield plans for Central Europe as a threat to its security. The United States says the missile shield is needed as protection from possible strikes from "rogue states."
Earlier this week, the United States and ex-Soviet Lithuania, a European Union and NATO member since 2004, admitted holding talks on the possible deployment of the missile interceptor base in the Baltic state if the U.S. deal with Poland falls through.