EU nations risk driving Christians and Muslims apart if Turkey is not brought into the fold, Foreign Secretary Jack Straw has predicted.
Foreign Minister Jack Straw supports Turkish EU membership
Mr Straw told BBC One's Politics Show: "We need to see Turkey in the European Union and not pushed the other way."
Formal membership talks are due to start on Monday but they are in danger of collapse, with Austria suggesting an alternative to full Turkish membership.
Austria says the EU has to address concerns about European expansion.
'Clash of civilisations'
But Mr Straw said giving Turkey membership was a way of "binding" Europe and keeping a membership promise made to the country in 1963.
"We're concerned about a so-called clash of civilisations," he said.
"We're concerned about this theological-political divide, which could open up even further down the boundary between so-called Christian heritage states and those of Islamic heritage."
Critics say Turkey's identity is more Asian than European
Most EU countries officially welcome the prospect of Turkish membership - albeit at least 10 years down the line and subject to consistent evidence of Turkey's commitment to democratic values.
However, public opinion in most EU countries appears, with varying degrees of intensity, to oppose Turkish membership.
Reasons for opposition include Turkey's large population (70 million and rising fast); its relative poverty and doubts about the compatibility of a country which has most of its land mass outside Europe.
There are also concerns about Turkey's attitude towards EU member Cyprus, which it does not officially recognise.
Diplomats say Austria is insisting Turkey be offered a partnership with the EU as an explicit alternative to full membership.
Turkey has said it will walk away rather than accept the Austrian offer.
But Mr Straw insisted: "We want Turkey to join the EU because it is a European country.
"It has been promised membership of the European Union for the last 42 years. We've repeated that promise five times in the last ten years.
"And in December 2004 and in June of this year [EU leaders] unanimously said that negotiations ought to start tomorrow - the aim of the negotiations is full membership."
The negotiations, whenever started, are expected to take about 10 years.
Turkey needs to make huge efforts to meet the stringent requirements for EU membership, including absorbing the 80,000-page EU rule book into its domestic law.
The European Commission has promised to monitor closely how Turkey proceeds. If it is deemed to be slipping backwards in theory or practice, then the commission will not hesitate to make its misgivings public.