Neighbourhood Policy Commissioner Stefan Füle has said there are increasing concerns about the pace of reform in Turkey, during presentation of the annual EU enlargement package on 10 October 2012.
The report says that the country's human rights situation "continues to be the source of serious preoccupation".
Turkey is one of a number of countries that have been given candidate status, meaning that negotiations on joining the EU have started or are imminent.
However no new discussions have taken place with Turkey in two years, and the EU has criticised the Turkish government's poor co-operation during the current presidency of the Council of Ministers, held by Cyprus.
Turkey is the only country to recognise the independence of the northern, Turkish-speaking part of Cyprus.
Other candidate countries - Iceland, Macedonia, Montenegro and Serbia - had mixed reviews.
Serbia was criticised for continually refusing to recognise the independence of Kosovo, a major sticking block in its membership prospects. The Belgrade government was also criticised for making very little progress towards developing its economy.
There were mixed prospects for countries seen as potential candidates.
Commissioner Füle has recommended that Albania should be given formal EU candidate status, although candidate status for Bosnia-Hercegovina and Kosovo remains a more distant prospect.
The enlargement package also contained a detailed monitoring report on Croatia, which will join the EU at the start of July 2013.
The Commission found that Croatia is making good progress with bringing its laws and institutions into line with EU norms, although it highlighted that certain aspects of the labour market still need reform.