Massive demand for Take That's 2011 tour saw several U.K. ticketing sites crashing today as fans clamored for the chance to see the re-formed pop group.

Tickets for the band's 14-date U.K. summer tour went on sale this morning at 9am GMT from a variety of online vendors, including Ticketmaster, See Tickets and Ticketline.

As soon as tickets went on sale, fans swamped the official ticketing sites -- leading many of the platforms to buckle under the strain. This morning, Ticketmaster, See Tickets and Ticketline were all either displaying error messages when attempting to process orders, or appeared to have crashed entirely.

"Due to totally unprecedented demand all ticket agents across the UK, including Ticketmaster, are struggling to cope with the sheer volume of people logging on to try and buy Take That tickets," said a statement posted on Ticketmaster's official Facebook page, which is accessible via a link from Take That's website.

"We are working to resolve the issues and we are confident that fans will be able to purchase tickets and we ask that they keep trying," the statement went on to say, adding that demand for tickets was having a knock-on effect on the U.K. telephone network.

Ticketmaster claim that call volume is double that experienced for Michael Jackson's ill-fated 2009 "This Is It" tour.

Police have warned fans not to buy from unofficial ticketing agencies. The BBC also reports that hundreds of fans have been queuing at venue box offices throughout the United Kingdom.

As previously reported, Take That announced that they would embark on a 20-date 2011 European tour at a press conference at London's Savoy hotel, earlier this week. (, Oct. 26).

The tour marks the first time in over 15 years that all five original members, Gary Barlow, Robbie Williams, Mark Owen, Howard Donald and Jason Orange, will have shared a stage. Tickets for European shows go on sale Nov. 5.

This week it was also confirmed that the release of the band's highly anticipated new album -- Take That's first with Williams since the mid-nineties -- has been brought forward to meet demand. The five-piece group made the announcement during an interview with stand-in breakfast host Scott Mills on national Top 40 station BBC Radio 1.

"Progress" (Polydor) will now come out in the U.K. Nov. 15. The release of lead single "The Flood" has also moved forward one week and will come out digitally Nov. 7 and physically the next day in the U.K.