The European Union needs to find ways of speeding up the membership process for six Western Balkan candidate countries, European Council President Antonio Costa said on Thursday.

"For us, the enlargement, namely to the Western Balkans, is the most important geopolitical investment that the European Union is doing," Costa said during a joint press briefing with Serbian President Aleksandar Vucic in Belgrade.

Albania, Bosnia-Herzegovina, Kosovo, North Macedonia, Serbia and Montenegro have been seeking to join the bloc for some time now but have yet to complete the stringent process.EU leaders meeting to find ways of making process 'faster and better'

"Tomorrow the European leaders will discuss with the leaders of the Western Balkans how we can improve our methodology to move forward faster and better," Costa said, stressing that this did not mean making the process "easier."

Costa went on to say that in order to "boost trust between each other," there should not be a "feeling of frustration from the acceding countries" and also from the EU.