With the general election less than a day away, about 200 postal ballots still not delivered by Royal Mail have left councils anxious.
Cardiff and Vale of Glamorgan authorities have said they are aware of a delay in the Penarth part of the Cardiff South and Penarth constituency.
While Penarth is in Vale of Glamorgan council territory, it is a part of Cardiff South and Penarth for Westminster voting.
Voting for Penarth is managed by Cardiff council, which has issued more than 56,000 postal ballot packs in recent weeks.
Both councils said they are concerned about the matter and are working with Royal Mail to identify the problem.
They said “initial communication” indicated a number of postal ballots were held up in Royal Mail’s sorting system.
The authorities said there are arrangements for Vale of Glamorgan residents who have not received postal ballots to collect them from Barry civic offices.
There they can be completed and submitted to ensure they can cast their vote.
Vale of Glamorgan council has asked people to get in contact if they have not yet received their postal vote.
