Several ticket booking websites slowed to a crawl or were forced offline this morning owing to the huge demand for the recently announced series of concerts by Madonna.

Ticketline.co.uk and Gigsandtours.com both experienced loading times of 30 seconds or more after 9am when tickets went on sale, while Getlive.co.uk reported similar loading times before going offline at 10.20am.

Getlive.co.uk also reported several server errors, which could have left many visitors unable to purchase tickets and obliged to go elsewhere.

"Madonna fans will have been looking forward to this day for a long time, but the overall performance of several key websites may have left many without tickets and disappointed," said Haran Sold, EMEA managing director at Keynote, a web optimisation firm that detected the problems.

"When you're talking a minimum of £80 a head, online ticket retailers all have a responsibility to ensure a high level of service even at peak periods of activity.

"The fans that experienced considerable slowdowns, or couldn't access websites in the first place, may well do their ticket shopping elsewhere in the future."

In contrast to the problems experienced by some retailers, Ticketmaster.co.uk and Theonlineticketshop.com held up well during the busiest periods of activity, and were not affected in terms of loading times or overall availability.

Equally, as people tried their luck on eBay, the eBay.co.uk ticket search page also achieved a steady performance and 100 per cent availability.