BRUSSELS, July 7 (Reuter) - The European Commission said on Friday it had failed to agree a date with Morocco for a sixth round of negotiations for a new fisheries agreement,despite greater optimism on both sides.

"It was not possible to fix a date," Commission fisheries spokesman Marco Zatterin said. "We need more time to find a solution."

Zatterin gave no details about what had prevented agreement.

Fisheries Commissioner Emma Bonino said after meeting Moroccan Prime Minister Abdellatif Filali on Thursday that she was more optimistic that a deal could be struck and hoped a date would be set during dinner talks.

Filali said the meeting was positive and that he would "possibly" return to Brussels next week for further talks.

The EU and Morocco have been deadlocked over Moroccan demands for sharp cuts in quotas and increased fish landings in Moroccan ports.

The agreement with Morocco is the EU's most important external fisheries pact, providing a livelihood for 28,000 people in southern Spain, the Canary islands and Portugal.

Filali also held talks on Thursday with the EU's Commissioner for southern Mediterranean Affairs, Manuel Marin, on a new political and economic association agreement.

The EU wants to keep the two issues separate while Morocco says they are linked.