There is an official bar on the festival site

Many knew about the ban on glass bottles, but the ban on drinks cans was a surprise according to some.

The can ban, on the last day, was in contrast to the other three evenings.

A festival spokeswoman said the rules were publicised beforehand and were there to protect the public at a standing-only event.

"Many young people come to enjoy the Tan y Ddraig/Dragons Fire evening and our aim is to ensure everyone enjoys themselves in a safe environment.

'Bit of a farce'

"The rules were similar last year, and will be the same again next year," the spokeswoman added.

The other evenings at the festival, which featured the likes of Shirley Bassey and Westlife, were not covered by the same rules.

Organisers said this was because they were mostly seated concerts, whilst the Tan y Ddraig evening only had promenade tickets.

Festival-goers queued as bags were checked on the way in

It was the seventh year of the festival, which is the brainchild of opera star Bryn Terfel.

The spokeswoman added that details of the ban were not put on the tickets because it was presumed everyone would know about the ban from last year.

It will be publicised on the festival website next year however.

But festival-goer Gwyn Roberts said it should have been clearly stated on the tickets.

"People were emptying the cans before going on to the field. It was a bit of a farce and should be sorted out before next year," he said

There were long queues as officials searched the bags of all festival goers on the way in.

Another festival-goer Ifan Prys said: "They did not announce the ban on cans until it was too late for many and it was chaos at the gates."

"It was also unfair as organisers refused to refund the cost of the ticket to those who decided they did not want to waste money by pouring their drinks away."