The weak pound and the impact of a 70th anniversary could lead to a record-breaking year at this year's Edinburgh festival season.

In the days before the Edinburgh Festival Fringe and the Edinburgh International Festival (EIF) officially begin this weekend, major Fringe venues are reporting double-digit ticket sales increases from last year.

The EIF is also selling more tickets than this time last year.

The Underbelly venues are experiencing 50% more ticket sales than this time last year, with the Assembly venues reporting a 30% rise.

The director of the Edinburgh International Festival also said that sales were up for several reasons.

Last year's festival saw a record haul of ticket admissions for the Fringe, which is bigger in size and scale this year.

The Fringe issues 2.475m tickets last year, and the EIF registered ticket sales of £4m.

Fergus Linehan, director, said: "Ticket sales are good, which was our biggest year ever, maybe three or four per cent up.

"You could argue that if you are coming from everywhere else in the world, it is cheaper.

"If you are a visitor, the hotels and the tickets have got 15% cheaper in the last two years.

"That's helpful, and Edinburgh is just growing as a tourist location, and its just very compelling. Edinburgh is the ultimate mini-break."

Mr Linehan said that both the staged and concert operas were selling well.

Ed Bartlam, director of Underbelly, said: "Our ticket sales are remarkably strong, we are up 50%, and that is a true figure.

"Which is very interesting for us. It's a couple of things: this is going to be a big Fringe, and I've heard other venues have had strong advance sales.

"There is a particularly strong programme, across the board."

He added: "There's no doubt that the weakness in the pound is helping people.

"I think, generally, there's probably been a dramatic rise in visitors to Edinburgh, outside the Fringe, and that has corresponded with a greater audience for the Fringe and that international audience is more likely to book in advance."

Bill Burdett Coutts, founder of Assembly, which is back to staging theatre and shows in the Assembly Rooms on George Street, said: "The fact that the Fringe keeps growing is extraordinary - I've always thought there was a finite audience and it would stop.

"In a way it's the internet of the cultural world: people want to do their own thing, so they go up and do their own thing."

On ticket sales, he added that he hoped that George Street would be more lively this year than last, and said he would like to see the entire street pedestrianised.