TICKET agencies have warned tennis's governing body that invalidating tickets resold by touts for the sell-out Davis Cup semi final featuring Andy Murray in Glasgow may be against the law.

The Lawn Tennis Association warned disgruntled fans who might contemplate paying inflated prices to get tickets from touts, that they might be voided, after many complained that tickets were being swiftly resold up to £1,399 each, over 14 times their original face value.

Fans had condemned the handling of the public sale for the big match against Australia at the Emirates Arena on September 18-20 and bombarded tennis's governing body with complaints.

A promised link failed to appear before the 7am ticket sale on Thursday and minutes later they were sold out - with one fan complaining one resale website was selling them for £1,399 each, over 14 times their original face value.

Hundreds of tickets became available through resale and ticket exchange agencies including eBay company Stubhub for up to £750, Viagogo for up to £700, and the Ticketmaster firms Seatwave and Get Me In! for £500 and £750 respectively.

The face value of tickets ranged between £40 and £95 for each day of the three day tennis clash.

The LTA warned disgruntled fans who might contemplate paying the inflated prices to get tickets from touts, that they might become invalid.

But Ticketmaster, which runs two of the resale sites criticised by fans, Seatwave and GETMEIN! say the Consumer Rights Act "makes it clear that the secondary market is legitmate".

A Ticketmaster spokeswoman added: "If event organisers cancel tickets, just because they have been sold on the secondary market they are potentially in breach of the law."

She added:"We operate a resale marketplace through Ticketmaster Resale sites Seatwave and GETMEIN! which are safe, transparent and lawful environments that respond to what fans want - the ability to buy and resell tickets when the primary supply is exhausted or purchasers can no longer use their tickets - as in this case for the Davis Cup semi-final.

"The word marketplace is very important here as our resale sites act as a platform for individuals to list their unwanted tickets at a price that they choose, these tickets can then be purchased by someone who is happy with that price.

"Prices through Ticketmaster Resale can be both above and below face value.

"Putting a cap on resale mark-up on the face value of a ticket is unworkable; the internet has no borders, and if you cap resale, the most sought-after tickets will be made available ‘underground’ or offshore. Experience from across the globe has shown that caps on resale prices are unenforceable.

"Consumers want the right to be able to sell tickets at a market price and the right to pay over the face value of a ticket if they really want to attend a sold out events.

"Consumers can be confident that tickets bought from – Seatwave and GETMEIN! will be valid. Our Fan Guard guarantee ensures that if purchasers face any problems with their tickets we will provide a replacements or a refund.

"The Consumer Rights Act, which has recently come into force, makes it clear that the secondary market is legitimate. If event organisers cancel tickets, just because they have been sold on the secondary market they are potentially in breach of the law.

Nick Harford, interim international general manager at StubHub said if there is any issue they will replace the tickets with comparable or better ones, or at the very least, refund the buyer's payment in full".

He added: "As it is perfectly legal to resell a ticket, tennis fans can be confident in buying tickets for the Davis Cup semi final through StubHub. We back every purchase made through our site with our market-leading FanProtect Guarantee."

The LTA had said after coming under fire that demand had been "extremely high and we are sorry that not everyone has been able to secure a ticket."

It added: "The LTA tries to ensure that tickets for its events are sold to genuine fans.

"The LTA takes the issue of unofficial ticket selling seriously. For the Davis Cup by BNP Paribas semi-final tie between Great Britain and Australia, The Ticket Factory is the only ticket agency authorised to sell tickets on behalf of the LTA.

"Selling tickets through unofficial means is against the LTA’s terms and conditions and may allow prices to be inflated and prevent many fans from attending. Anyone considering buying tickets from the unofficial sources runs the risk of being unable to enter on the day as the ticket may have been cancelled."

The LTA did not respond.