Füle was speaking after the sixth meeting of the EU-Croatia Stabilisation and Association (SA) Council, held in Brussels and chaired by Croatian Foreign Affairs Minister Gordan Jandroković.
The commissioner praised Croatia's progress since accession talks began in 2005, but cautioned that steps still need to be taken in a number of difficult areas - particularly the judiciary, public administration, corruption and minority rights.
He said Croatia must make every possible preparation to join if it is to benefit fully from membership, stressing the importance for ensuring quality over speed in EU enlargement policy.
The joint EU-Croatia Council reiterated the view that Croatia should be able to finalise its accession negotiations by the end of 2010, provided that all the necessary political, economic and legislative reforms are completed.
Two new negotiation chapters have been opened since the last meeting in April 2009 - fisheries and the environment. 30 out of 35 chapters have now been opened, with 17 already closed.
Attention now turns to the three legislative chapters that are yet to be opened: competition, the judiciary and fundamental rights, and foreign, security and defence policy.
Spanish Secretary of State for Foreign Affairs Angel Lossada, the EU's delegate at the meeting, said the Spanish EU Presidency was aiming to close as many chapters as possible during its six-month tenure at the bloc's helm.
The Spanish Presidency also hopes to make real progress on the unopened legislative chapters, including the ''demanding'' competition chapter, in the next three months, he added.
Lossada said member states are still fully behind Croatia's entry, describing this pro-accession stance as a positive signal for other aspiring EU members in the Balkans.
Meanwhile, a working group has been set up to draft Croatia's accession treaty and a communication from the European Commission on the related financial package.
Slovenian court approves border agreement
Also on Tuesday (23 March), Slovenia's constitutional court approved an arbitration agreement between Slovenia and Croatia on a long-running border dispute that stalled the latter's EU accession talks last year.
The prime ministers of both countries signed an accord on the issue in September 2009 and the court's decision that it is in line with Slovenia's constitution removes a significant obstacle to Croatia's EU membership bid.
Croatia has already ratified the border agreement and this week's ruling in Ljubljana paves the way for full ratification in the Slovenian parliament.
