The European Union has agreed to open the first cluster of accession talks with Ukraine and Moldova on Monday, marking a major step in the bloc's enlargement.

Experts say such negotiations are typically lengthy and complex, and that the opening of talks does not mean the two countries will join the EU anytime soon.

European Council President Antonio Costa and European Commission President Ursula von der Leyen announced on Friday that all EU member states have agreed to open the first accession negotiations cluster on fundamentals with Ukraine and Moldova.

The talks would cover areas including the rule of law and democratic institutions, which are the backbone of the EU accession process.

"This is a recognition of the determination, courage and hard work shown by both countries in advancing reforms, even in the face of immense challenges," the statement said.