The workers have walked out over pay rates

About 750 members of the Usdaw union were walking out from the Haydock depot at 2200 GMT.

The depot supplies produce to Sainsbury's stores in the north of England.

The workers voted to take the action because the supermarket chain's hourly pay rates are lower than those of workers with similar firms in the region.

But Sainsbury's said it did not expect the walkout to affect customers in its supermarkets.

Staff are angry the current �5.75 an hour has not been increased to the regional average of �8 an hour, but to �7.55.

'Door open'

Usdaw national officer Joanne McGuinness said: "We are keen to reach an amicable solution to this and have held four days of talks with Sainsbury's since the last strike."

She said the door was being kept open for further negotiations.

Before the first strike, a Sainsbury's spokesman said: "Haydock is one of 20 depots and we are able to move product throughout the network.

"We are offering a very competitive performance related package which, compared with competitors, is one of the best in the area.

"In addition we have given an above inflation pay rise for the last three years."