The BBC has apologised after a technical problem left some viewers with no sound or dialogue for the dramatic closing moments of Doctor Who’s series 10 finale.

Viewers complained online that their audio cut out in the climactic final scenes of BBC1’s Saturday night sci-fi, leaving people unable to hear Peter Capaldi’s shock reunion with a character from Doctor Who past (no spoilers for those who haven’t seen – or heard – the episode).

Can't believe the sound problems in the last moments of tonight's episode of #DoctorWho. Was so wrapped up in the moment 'til then.

— Mark Dodyk (@Mark_Dodyk) July 1, 2017

Loved #doctorwho finale -Peter C class act -didn't love no dialogue sound in last few scenes @BBCScotland ?? 12yr old son wants answers @BBC

— Fiona Hyslop (@FionaHyslop) July 1, 2017

We understand that the problem only affected viewers watching on BBC Scotland HD, with broadcasts in other parts of the country or standard definition in Scotland unaffected.

The issue was not related to the episode’s sound mix, a source told RadioTimes.com

The BBC’s official Doctor Who Twitter feed apologised to those who experienced problems and said it was looking into what caused the sound to cut out.

Many apologies to anyone who experienced problems with the sound on The Doctor Falls. We're looking into what went wrong. (1/2)

— Doctor Who (@bbcdoctorwho) July 2, 2017

The Doctor Who series 10 finale – free of any sound issues – is available to watch now on BBC iPlayer.