Shoppers attempting to book a Christmas delivery slot on Tesco.com have reported website crashes and hours-long wait times to reach the front of a queue of close to 300,000 people.

Some claim the queue was opened before the scheduled time of 6am yesterday, with others reporting they were kicked off the website the moment they reached the front of the queue.

Tesco told complainants on Twitter it was “seeing an unprecedented volume of traffic on our website and because of this some customers are temporarily experiencing a problem when logging onto our website or placing orders”.

The supermarket implemented a “temporary limit” on the number of people using the website to manage the heightened demand on its systems.

Tesco scrambled its IT teams to resolve the issues and urged shoppers to “keep trying to book a slot”.

Priority access to Christmas slots has so far only been issued to Delivery Saver customers, who pay an annual or monthly fee for the perk. These deliveries can be scheduled to arrive between December 20 and 23, and on Christmas Eve from selected stores.

All other customers can book any remaining Christmas slots from 6am on 22 November.