But its 25 leaders were still debating the issue of Turkish recognition of Cyprus, with the Greek Cypriot government insisting Ankara normalise ties with Nicosia before the proposed starting date for EU negotiations.
EU leaders agreed on Thursday that the aim would be membership rather than any privileged partnership but no outcome would be guaranteed, the diplomats said.
If talks failed, the EU would seek other ways of tying NATO member Turkey, viewed by Washington and others as a key Western ally, into European structures.
"We are going to go ahead on 3 October (2005 ) to allow Turkey and the Turkish parliament to recognise Cyprus," Italian Prime Minister Silvio Berlusconi said.
'Very good offer'
Leaders arriving for the Brussels summit had expressed confidence they would reach agreement on offering talks for the largely Muslim and agrarian nation of 70 million, which sits on the hinge of southeast Europe and the Middle East.
"If you want to be part of a family you have to recognise all the members of the family. Without that it's difficult to be part of the family"
EU foreign policy chief
European Commission chief Jose Manuel Barroso urged Turkey to accept the offer to start negotiations.
"We believe this is an offer Turkey should be glad to accept," Barroso told a news briefing after European Union leaders held talks, adding they had made Ankara "a very good offer".
Turkish Prime Minister Tayyip Erdogan said his government "could have a positive attitude" to the EU's demands over the divided Mediterranean island - but only after the current summit talks expected to give Ankara a conditional "yes" to accession talks.
Cyprus is one of the biggest stumbling blocks to Turkey's hopes of seeing its four-decade drive to be embraced into the European fold reach fruition at the Brussels talks.
The island has been divided along ethnic lines since 1974, when Turkish troops occupied its northern third. Ankara only recognises the breakaway Turkish Republic of Northern Cyprus (TRNC).
The Republic of Cyprus led by Tassos Papadopoulos joined the bloc alone on 1 May after its voters rejected a UN peace plan enthusiastically backed by people in the TRNC and by Ankara which would have reunified the island.
Turkish officials say there is
room for debate over Cyprus
Turkey argues that by backing the reunification plan crafted by UN chief Kofi Annan, it has done enough and it is now up to Papadopoulos' government to move to restore hopes of peace.
Moreover, recognition of Cyprus has never been formally demanded of Turkey by the EU as a price for launching accession negotiations.
But EU foreign policy chief Javier Solana said common sense required Turkey to recognise Cyprus now that the island is in the 25-nation bloc which Ankara wants to join.
"If you want to be part of a family you have to recognise all the members of the family," he said. "Without that it's difficult to be part of the family."
The EU leaders were expected to require Turkey to show implicit recognition of Cyprus by calling on it to sign an additional protocol to its 1963 association accord with the EU's forerunner.
The protocol to the Ankara Agreement would extend the pact to cover the 10 nations that joined the EU in May, including Cyprus.
Danish Prime Minister Anders Fogh Rasmussen said: "I would find it natural that Turkey signs the so-called Ankara Agreement before accession negotiations start."
But he added: "The present political leadership (in Cyprus) has not eased the situation by opposing the Annan referendum."
Firm but flexible
Erdogan, in an interview with French television station TV5 given from Brussels, said his government could show flexibility on Cyprus but would not allow recognition to become a pre-condition at the two-day EU summit talks.
"If this point is pressed up to 17 December (Friday), that will not be admissible. But after 17 December we could have a positive attitude"
Turkish prime minister
"If this point is pressed up to 17 December (Friday), that will not be admissible. But after 17 December we could have a positive attitude," Erdogan said.
Agreement by all 25 EU states is required for an agreement to launch accession negotiations with Turkey, handing Cyprus a potential veto.
Before leaving for the crucial summit, Papadopoulos said in Nicosia that he was "prepared for tough negotiations up until the last moment".
"We will do everything that we think is right for Cyprus and judged to be in the medium- and long-term interests of the Cypriot people," he said.
For Cyprus, the summit would be "a major turning point, but we are not calling it an issue of life or death", he added, leaving open hopes of a deal later on if Turkey promises for now to move on the recognition issue.