Israel's indirect negotiations with Syria through Turkish mediators are making it harder for Jerusalem to argue against high-level European contacts with Damascus, diplomatic officials said Sunday. The officials' comments came as Prime Minister Ehud Olmert's chief of staff, Yoram Turbowicz, and his foreign policy adviser, Shalom Turgeman, traveled to Turkey for another round of indirect talks with the Syrians. Neither the locale nor the framework of the talks were formally confirmed by the Prime Minister's Office. Also Sunday, two top advisers to French President Nicolas Sarkozy met with Syrian President Bashar Assad in the latest sign of a thaw in ties between the two nations. The ElysÃ©e presidential palace said those talks were "useful and constructive" and focused largely on bilateral ties, Lebanon, Israeli-Syrian relations and an upcoming Union for the Mediterranean session. The meeting Sunday in Syria included ElysÃ©e secretary-general Claude Gueant and Sarkozy's chief diplomatic aide and sherpa Jean-David Levitte. The talks took place as US President George W. Bush wraps up a three-day visit to France. Bush and Sarkozy have spoken with one voice on Syria. Bush warned Assad to "stop fooling around with the Iranians and stop harboring terrorists." Even though Israel is now openly holding indirect talks with Syria, it is not keen on seeing Damascus break through its international isolation without having to pay anything in return. However, the talks in Turkey are making it more difficult to demand that the Europeans continue to keep Syria at arms-length. According to diplomatic officials, one argument the French have used to justify the meeting of Sarkozy's advisers with Assad was "if the Israelis are talking with the Syrians, why can't we." Israel, according to the officials, is not actively trying to convince the French and other Europeans to continue isolating Damascus, but is rather advising caution, saying that any steps taken in Syria's direction must be measured against whether Damascus has shown any signs of moderation, or taken any steps to kick the terrorist organizations out of Damascus, or to move out of Iran's orbit. "What we are saying is not to give up any assets until something is received in return, that there is a need to check against delivery," the officials said. Israeli officials also said it was likely that Assad would attend a conference in Paris on July 13 of potential members in a union of Mediterranean states that Sarkozy is pushing. This conference is expected to be attended by some 40 heads of government - 27 from the EU and about a dozen more from other countries bordering the Mediterranean Sea - and would provide Assad with a huge boost in trying to break his isolation. Olmert has already indicated that he would attend the conference. Sarkozy's original idea, one he put forward even before he was elected French president in May 2007, was to bring 20 countries around the Mediterranean into one regional union. That idea has morphed into a regional association that would include all the EU states and the states bordering the Mediterranean to deal with a variety of common issues. Algeria and Lebanon have indicated that they would not attend the conference because of a concern that the union would constitute a normalization of ties with Israel. Diplomatic officials, however, said that at least in Algeria's case, Israel was a convenient excuse for not attending, but the real reason was because it was vying with a number of other countries - including Morocco and Libya - to host the headquarters of this new body. AP contributed to this report.