Foreign ministers of the European Union (EU) said disagreements on some key issues still exist concerning a new EU treaty after their night talks here on Sunday.

Speaking to reporters following the night discussions, Portuguese Foreign Minister Luis Amado said that "on some key points, we have (made progress), but on some others, we did not."

"I believe the German (EU) presidency will be able to tackle these," he added.

However, he declined to go into details about the progress on the issue.

The EU foreign ministers, who will continue their talks on Monday and Tuesday, are here to make preparations for the EU summit scheduled for June 21-22 with the "road map" for a new EU treaty high on the agenda.

EU leaders have stepped up their diplomatic efforts these days to narrow differences over the contents of a new EU treaty, which is designed to replace the EU constitution, whose ratification process was stalled after rejections by French and Dutch voters in referendums in 2005.

Amado said all the leaders of EU countries have "a sense of responsibility" and "are prepared" to hammer out a deal on a new EU treaty.

"In the end, we will have an agreement," he said, adding he was paid to "be optimistic and not pessimistic."