LONDON (Reuters) – Britain's second largest supermarket, Sainsbury's, pledged to halve plastic packaging by 2025 on Friday, promising to switch to alternative materials and refillable options to meet consumer demand for less waste.

With plastic packaging reduced by only 1% in 2018, Sainsbury took a "rethink" to tackle the nearly 120,000 tonnes of plastic packaging consumed each year.

It was said to have used most plastic in milk bottles, packaging for fruits and vegetables and drinks. Milk bottles are tested for options, including the use of returnable bottles, reusable milk bottles or offering a reusable jug of milk in a lightweight plastic bag.

With 178,000 employees across the country, Sainsbury will attend a summit meeting with suppliers, researchers and government groups on Friday to identify areas for a breakthrough.

"Reducing plastic and packaging is not easy," said CEO Mike Coupe. "Packaging plays a vital role in the safety and freshness of our food and in minimizing food waste.

"We therefore need to find alternatives to plastic that protect the quality of our food while minimizing its impact on the environment."

The British have become increasingly aware of the amount of plastic used in David Attenborough's "Blue Planet II" documentary, highlighting the dangers of plastic pollution for life in the sea.

In recent years, the UK has succeeded in reducing the use of plastic bags by charging 5 pence for each bag, and the government has considered making a "latte levy" on disposable coffee cups that are difficult to recycle are.

Britain's largest supermarket, Tesco, has also stepped up its efforts to encourage customers to recycle plastic bottles by testing recycling machines in the shop to pay customers for every returned bottle.

(Reporting by Kate Holton in London, editorial by Matthew Lewis)