Tesco's website and app have crashed after what the retail giant said were attempts "to interfere with our systems".

The possible hack at Britain's biggest supermarket began on Saturday with shoppers unable to order goods and track deliveries.

Tesco initially said there was "an issue", but in a Sunday update said there was a deliberate disruption.

The retailer sought to assure customers their data was safe.

A Tesco spokesperson said: "There is no reason to believe that this issue impacts customer data and we continue to take ongoing action to make sure all data stays safe.

"Since yesterday, we've been experiencing disruption to our online grocery website and app.

"An attempt was made to interfere with our systems which has caused problems with the search function on the site. We're working hard to fully restore all services and apologise for the inconvenience."

The scale of the problem had been unclear on Sunday morning, or if the troubles were nationwide or in certain areas.

According to Downdetector, which monitors website outages, shoppers began reporting issues on Saturday morning.

Image source, Russell Hotten

Tesco initially said it was "working hard to get things back up and running", and apologised for the inconvenience.

Shoppers had complained about a lack of information, with many wanting to know how to cancel orders and whether they would get money back.

Tesco's online sales have soared, especially during lockdown, with the supermarket ramping up capacity.

The firm's latest financial results say the scale and reach of its online operations are "unmatched in the UK", with total sales topping £6bn. Tesco said it had 6.6 million app users.