Serbia agreed to answer the Commission's questionnaire by the end of January 2011.
Replying to the 2,483 questions, divided into 33 policy areas, may appear as an overly-ambitious task. The questions alone go on for more than 400 pages.
But Serbian Prime Minister Mirko Cvetković said his country wanted to set foot on the EU track in a very short timeframe.
"The government's aim is for Serbia to obtain EU candidate status by the end of 2011 and to determine the date for the beginning of negotiations," Cvetković stated.
In 2011, the EU's rotating presidency will be held by Hungary and Poland. Both countries are favourable to EU enlargement to the Western Balkans and begin EU negotiations with Serbia as soon as possible.
Once Serbia has returned the questionnaire, the EU executive will begin a process of issuing an opinion, which takes about one year.
Iceland was the only EU candidate country to start negotiation talks, just one year after its application. But Commission representatives insist that Iceland is a special case, as the Nordic country has already taken on board a lot of EU legislation as a member of the European Economic Area (EEA).
Serbia has entered a new phase in its relations with the EU, Füle said, adding that full cooperation with the International Criminal Tribunal for the former Yugoslavia (ICTY) remains an important element in Serbia's EU integration (see 'Background').
The commissioner urged the Serbian authorities to give "top priority to tracking and arresting" war criminals Ratko Mladić and Goran Hadžić.
The authorities say they cannot locate the fugitives. In a recent interview for EurActiv, Hungarian MEP György Schöpflin (European People's Party), shadow rapporteur on Serbia, suggested that Mladić and Hadžić are hiding in Republika Srpska, the Serbian entity of Bosnia and Herzegovina.
When asked by journalists, Füle said the EU questionnaire does not cover the territory of Kosovo, a former Serbian province that unilaterally declared independence in February 2008. But he added that the questionnaire contained specific questions concerning Serbia's dialogue with Pristina.
The commissioner recognised Serbia's progress in regional cooperation, as well as in the fight against corruption and organised crime.
Last September, Serbia showed a more cooperative attitude toward Kosovo, supporting a UN compromise resolution on Kosovo fine-tuned by EU diplomats, and dropping its earlier demands to reopen talks on the status of its former province.
These symbolic steps have made the resolution of outstanding issues between Belgrade and Pristina look like a realistic prospect. However, the unprecedented political vacuum left by the resignation of Kosovo's president last September and the no-confidence vote given to the government in early November threatens to slow the momentum of a rapprochement with Serbia.