TIRANA -- U.S. Secretary of State Colin Powell on Friday signed a charter with the Balkan states of Albania, Croatia and Macedonia that is seen as an essential step in their bid to join NATO.

"Every European democracy that seeks NATO membership and is ready to share NATO responsibility should be welcomed into the alliance," Powell said following the signing of the so-called U.S.-Adriatic Charter.

The U.S. State Department has said the charter is intended to help the three countries "to eventual full integration into Euro-Atlantic institutions," especially NATO.

"This charter will serve as a roadmap to them on their path to Euro-Atlantic integration as well as a guide of our collective efforts to help them achieve their aspirations," said Powell, who stopped off in Albania on his way to Syria to push the U.S. agenda in the Middle East following the Iraq war.

"It underscores the importance we place in their eventual full integration into NATO and other European institutions," he added. Albanian Prime Minister Fatos Nano said the charter would boost cooperation with the United States and "serve to strengthen peace and stability in our region."

Albania was among the first of the Central and Eastern European countries to back the U.S.-led war on Iraq, stating it was ready to open up its air and naval bases for use by NATO and coalition forces.

An Albanian Army unit is among the special troops sent into Iraq in mid-April to participate in postwar peacekeeping operations under U.S. command.

Washington has already invited Tirana to take part in the reconstruction of Iraq, a potentially lucrative offer now under close scrutiny of businessmen Albania, which is still one of the poorest and least stable in Europe more than a decade after emerging from hardline communist isolation.

Also Friday, Powell signed an agreement with Albania giving U.S. citizens immunity from prosecution by the new International Criminal Court (ICC), the world's first permanent court set up to try cases of genocide, war crimes and crimes against humanity.

Washington opposes the court and has been on a worldwide campaign to sign such immunity deals, arguing that the ICC could become a forum for politically motivated prosecutions against U.S. citizens, including civilian military contractors and former officials.