Voting rights in Malta and the UK

I am unsure of the rights afforded to foreign nationals who reside in other EU countries with regard to their voting rights and the procedure to adopt to ensure that they are legally included in any electoral register of those countries. However, I am in a position to categorically state the position of such with regard to British and Maltese nationals residing respectively in each others' countries.

In the UK, a Maltese citizen whose name appears on the electoral register is granted permission to continuously remain on said register until such time as they advise the authorities otherwise, for there is absolutely no requirement to ever reapply as various elections arise. Moreover, Maltese subjects enrolled on the UK electoral register are granted the privilege of being allowed to vote in each and every election, including the parliamentary (general) election, and are not confined (restricted) to local council - or EU- related elections.

These UK voting rights and privileges granted to Maltese citizens residing in the UK are regrettably and unaccountably not reciprocated by the Maltese authorities to UK citizens living in Malta, whose name appears on the Malta electoral register.

Could the authorities kindly explain why such discrimination and non-reciprocation exists? Furthermore, will they indicate where such provisions appear in the European Parliamentary law statute, allowing such anomalies?