New Delhi, Nov. 5 -- The European Union on Tuesday praised Ukraine's progress on reform to join the bloc despite concerns over its efforts to tackle corruption, and issued tough warnings to candidates Serbia and Georgia about democratic backsliding.

In a series of enlargement reports, the bloc's executive branch, the European Commission, also said that Montenegro could wrap up its EU membership talks by the end of next year, leaving it first in line to become the 28th member country.

Presenting the reports, EU Enlargement Commissioner Marta Kos said the progress toward membership made by Ukraine and Montenegro, but also Albania and Moldova, "shows that reforms pay off. This should serve as a strong motivation for all countries engaged i...