Thousands of supermarket Christmas trees are being recalled because of a potentially lethal electrical fault with their lights.

Asda said it was asking customers to return more than 10,000 of the pre-lit trees it has sold in shops across the country. It had also withdrawn another 50,000 from shelves and warehouses.

A spokesman said four customers had returned the plastic trees, which come in three colours and are priced between £15 and £27, and complained that some of the light bulbs were damaged.

He said bulbs were already smashed exposing an element which would cause a "nasty" electric shock if touched when the tree was plugged in to the mains.

"We have not come across any [smashed bulbs] in the trees that we have checked in depots and in stores but this is a result of customers bringing them back.

"We couldn't even have one tree out there that could potentially give someone a nasty electric shock so that is why we have recalled all of them," he said.

The firm has withdrawn around 50,000 of the products from its shelves and depots and is offering a refund to customers who return them.

Asda stressed that nobody had been hurt. The spokesman said: "Despite our rigorous quality standards Asda has found that these pre-lit Christmas trees we've been selling do not meet our high standards."

He added that the trees, which were made in China, carried the Asda brand but were supplied by a company called Puleo Asia.

The affected trees have the following product names and prices: Pre-Lit Pine Christmas Trees 6ft. £15; Pre-Lit Black Christmas Trees 6ft. £27; Pre-Lit White Christmas Trees 6ft. £27.