The supermarket milk price war intensified further this week, as Morrisons revisited a rock-bottom promotion on 1% milk, selling four pints for 50p.

The supermarket ran ads in the national press to highlight the new price, ­under the headline 'Britain's cheapest milk?'.

Morrisons' move comes after Tesco raised the price of four pints of standard from £1.25 to £1.49 on 31 May, followed by price increases in Sainsbury's and Waitrose.

Following Tesco's increase to £1.49, Asda still selling at £1.25 as The Grocer went to press ran an ad highlighting the price difference between its milk price and Tesco's. However, Tesco continues to sell four pints for £1 ­under its tertiary Creamfields brand.

Morrisons said its 50p promotion was for a limited time only, and it was not paying its farmers any less as a result.