Deputies expressed their concern during a debate in parliament on British ratification of Croatia's EU accession treaty. The ratification process in Britain began on October 18 and should be finalised by spring next year.

Even though Croatia enjoys wide support in the British parliament, opposition Labour and ruling Conservative party MPs have expressed concern that Croatia could become an entry point for human traffickers and illegal migrants and that perhaps Croatian police are not up to deal with such an influx.

MPs referred to a recent EU report and consider shortcomings in Croatia's judiciary and police force, the European Arrest Warrant, a protocol for extraditing criminal suspects as an extra worry.

Labour MP Michael Connarty noted: "Again and again, we are getting strong warning signals that Croatia is not yet in a good place to enter the European Union."

On the other hand deputy foreign minister David Liddington defended Croatia's readiness to join. "We have not identified any victims of trafficking from Croatia in the United Kingdom", he said.

He noted that Zagreb was dealing with corruption at the highest levels, including former PM Ivo Sanader and former defence minister Berislav Roncevic.

Roncevic was sentenced to four years imprisonment for the "truck affair" while trials for corruption against the former PM are still in process and the first ruling is expected on November 16.

Liddington added that Croatia is not expected to file an application to join Schengen, the EU's passport-free zone, until 2015, and that the UK will impose limits on Croatian workers who want to come to Britain for "at least" the first two years of its EU membership. He added that the EU could always punish Croatia should it slide back into bad habits.

Another nine EU countries are yet to ratify Croatia's accession treaty. Most countries are waiting for the final European Commission monitoring report due next spring before finalising ratification.