"We are so focused on the quality of accession negotiations that speculation about an eventual monitoring mechanism does not have any place and I take my responsibilities very seriously in this regard. I am not in the business of running an accession process that requires such a mechanism," Fuele said when asked if monitoring mechanisms like those put in place for Bulgaria and Romania were envisaged for Croatia.

Twice a year the European Commission monitors the progress made by Bulgaria and Romania in the reform of the judiciary, the fight against corruption and, in the case of Bulgaria, the fight against organised crime. The measures were introduced after it became clear that the two countries were not fully prepared for membership.

Fuele said that "many lessons have been learned" from past enlargements, adding that the focus was now on "benchmarks" for closing negotiating chapters and guaranteeing that the EU hopeful was fully prepared to join the bloc.

The commissioner would not confirm that such a position was the result of the case of Bulgaria and Romania.

Asked whether "lessons learned" meant learning from mistakes made in 2007, when Bulgaria and Romania joined the EU, Fuele replied, "No, I think that the whole enlargement was generally a success".

"Each and every accession process has had its challenges and I use this phrase again - 'lessons learned' - because we want to apply these lessons to the next enlargement to make it even more streamlined and more effective. This is exactly what we are doing with Croatia," he said.

Fuele said there were no challenges ahead that Croatia could not cope with.

"Croatia has made excellent progress in recent months and we are very much in the final stage of accession negotiations. I cannot see any issue or challenge that Croatia won't be able to overcome with the assistance of the European Commission," Fuele said.