Turkey's Islamist-rooted government faces making a difficult decision that pits maintaining good relations with its neighbours against joining a NATO missile shield directed against Iran.

Prime Minister Recep Tayyip Erdogan has sought in recent years to boost Turkey's ties in the region -- raising suspicions he is moving the country out of the West's orbit -- and will now have to make a decision that will be viewed as a test of its commitment to its NATO partners.

The US plan to build a network of ballistic missile interceptors in Europe has been taken up by NATO, partly in order to convince reluctant members of the alliance to join the project.

The Turkish government will have to stop fence-sitting soon as NATO chief Anders Fogh Rasmussen wants a final decision on the missile shield to be made at a summit of the alliance's leaders on November 19 and 20 in Lisbon.

The United States says the shield is meant to protect against an eventual missile strike from Iran, but has been vociferously opposed by Moscow, which fears it could undermine its nuclear deterrent.

This poses a problem for Ankara, which fears joining the missile shield will damage relations with Moscow and Tehran, which have improved considerably in recent years, according to analysts.

"It is a dilemma for Turkey. On one hand you have a policy of maintaining friendship with our neighbours, and on the other you are going to be deploying arms which target them," said Sinan Ogan, director of the Turksam think tank in Ankara.

When the defence and foreign ministers of Turkey and the United States met Thursday in Brussels on the sidelines of a NATO summit, the missile shield was at the centre of the talks, Turkish media reported, with Turkish officials still "reserved" about joining the project.

Upon his return to Ankara, Turkish Defence Minister Vecdi Gonul rejected that term, saying Turkey welcomed the discussions within the alliance on the shield that could be operational by 2015.

US Defence Secretary Robert Gates was also quoted by Turkish media as saying that Washington was not putting pressure on Ankara to join the project, but was continuing to hold discussions.

Erdogan also said Friday there had been no pressure on his country.

"No demands have been made of us on this matter, so there is no question of us being given a fait accompli" in Lisbon, he said.

"Turkey has not come to a decision yet, there are technical problems to surmount," a Turkish diplomat told AFP on condition on anonymity, saying Ankara was trying to figure out a way to minimise the impact of a "yes" decision, particularly for its relations with Tehran.

Ankara is in particular opposed to the shield being seen as targeting one country, and wants that it protects all of Turkey against a missile attack, not just areas near the Iranian border, said the diplomat.

The question is even more difficult given the suspicions that Erdogan has been trying to move Turkey out of the West's orbit.

Turkey's refusal to allow US troops to cross its territory to invade Iraq in 2003, to support UN sanctions against Iran, and the ferocity of its dispute with Israel over the raid on a humanitarian aid flotilla to Gaza have all raised concerns about where Erdogan intends to take Turkey.

"A 'no' would only serve to confirm the idea that Turkey is in effect moving away from the West," said Ogan, who believes that the Turkish government will in the end likely decide to join the missile shield project.

The decision is also delicate as Washington remains an important ally for Ankara, particularly its support for Turkey's battle against the PKK Kurdish rebels, said Deniz Zeyrek of the Radikal newspaper.

Washington has been providing intelligence to Ankara about the movements of PKK rebels in northern Iraq, which they have been using as a rear base.