Plans for the Nato missile shield to single out Iran as a threat are unacceptable, and against the principles of Nato according to Turkish President Abdullah Gul.
"Nato is a defence organisation. A defence system is being developed against anyone in the world who has ballistic missiles and does not belong to Nato," he said.
The president told the BBC that targetting a particular country was wrong and unacceptable, and that the issue will be high on the agenda of a Nato summit to be held in Lisbon next week.
Turkey, Nato's sole Muslim-majority member, wants the missile shield to protect all of its territory, and not just areas near the Iranian border, Agence France Presse reports, quoting the diplomats.
The country is also worried that the project may affect the ties with its eastern neighbour Iran and Russia.
Nato and the US are planning to set up a missile shield to protect Europe against the growing threat of short and medium-range missiles possibly launched from the Middle East, especially from Iran.