The two-day European Council summit beginning 25 June, will see Prime Minister David Cameron explore official renegotiations on UK's EU membership.

Although this may probably not be considered at the working sessions of the summit, as EU leaders will want to address the burgeoning immigrant issue and the Greek crisis at the earliest.

Nonetheless, Cameron will be hoping that the process to find solutions to UK's priorities, which include restrictions on welfare entitlements, more powers for national Parliaments and an opt-out for Britain from the "ever closer union", gets underway.

He will also want to settle the issues before placing the revised package for a referendum before the citizens in 2017.

The European Commission has appointed a senior British official to head a new Brussels task force on the UK referendum, which will begin its work on 1 September.

On Wednesday, the Queen who is on a visit to Germany, called for unity in Europe and how the continent must strive to "maintain the benefits of the post-war world".

Mirroring sentiments, German President Joachim Gauck said that EU "needs Britain".

However, there is criticism in some quarters that Britain is cherry-picking the EU membership, seeking benefits with no risks.

The Greek debt and migrant crisis are expected to hog the limelight at the summit, with major disagreements on handling the latter.