Those with appointments or dropping in at the Glasgow Central Mosque in the Gorbals on Sunday stood outside waiting to be accepted into the vaccine centre, with some waiting as long as two hours.

When inside, patients say they were warned the centre was understaffed and there was a “shortage” of Moderna doses, extending the wait even further for those reliant on the vaccine brand.

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However, a spokesperson for NHS Greater Glasgow and Clyde (NHSGGC) denied the claims and insisted there were no supply issues for any jab brand over the weekend.

One patient who arrived at 12.30pm for a 12.50pm appointment told how he waited outside for around an hour.

He said: “I stood in the queue for ages and everyone around me was asking what time others had their appointments as everyone was getting close to their time or was already behind.

“When I got inside, I was asked what vaccine I needed and, when I explained I needed a second Moderna dose, I was told there was a shortage.

“I was sat at an empty table and told someone would be over when the vaccine was available.

“Eventually, I got my jag and I got outside about 2pm – over an hour after my appointment time.”

Another witness says queues began as early as 11am, with staff informing patients they were struggling to meet the high numbers of drop-ins.

Staff working outside the centre confirmed a busy morning had prompted them to form two queues in a bid to separate those waiting on set appointments from walk-ups in a bid to prevent delays.

The patient added: “It was a total shambles. Even staff were saying it was all over the place.

“I don’t know what was going on with the Moderna but that was just adding on to waiting times so people were getting quite annoyed.

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“It’s irritating when you have an appointment and you’re on time for it that you end up waiting around for so long.”

A NHSGGC spokesperson insisted there wasn’t a shortage.

They said: “These claims are incorrect. There were no significant queues and no shortage of any vaccine product at the site on Sunday.”