People have been lining up to vote in many polling stations abroad, Bulgaria's electoral authorities report as the country is choosing its next President.

In addition, a claim of ballot shortage has been filed with the election watchdog, Focus News Agency has quoted the Central Election Commission (CEC)'s spokesperson Tsvetozar Tomov as saying.

He has suggested the development may stem from the new election rules, with the latest changes having made it compulsory to vote.

The claims refers to "several sites" abroad, even though it has not been specified which countries they are in.

But voters in the UK have been complaining of flaws in the organization, some having to wait for hours to cast a ballot.

A London-based Bulgarian national, waiting to vote in the Stratford polling station, has spent more than three hours in a queue.

He has argued the organization is deplorable as it takes much more to vote than on previous occasions.