A new supermarket watchdog is being asked to probe the big retailers'  relationships with their suppliers and the pressure they exert on pay. 
Unite, the country's largest union, has written to Christine Tacon, the recently appointed Groceries Code Adjudicator, asking her to investigate four aspects of supermarkets' relationships with farmers and growers.
Unite is fighting to retain the Agricultural Wages Board (AWB) which has protected the incomes of 150,000 agricultural workers since the WWII. The union fears the major supermarkets are behind government plans to abolish the AWB and as a result, drive down pay.
Unite wants the probe to look at:
*The relationship between supermarkets, their suppliers, and the pay and conditions of workers employed by those suppliers.
*The links between supermarket pricing regimes and the abolition of the AWB, including analysis by respondents to the governments consultation on AWB abolition that unfair prices paid by supermarkets are leading suppliers to look for profits by cutting workerspay.
*The supermarkets ethical codes of responsibility which should be reviewed in light of what is happening to the AWB.
*A food and farming system that is fit for the future should have fair treatment for its workers at its heart.
In her new role, Ms Tacon will be responsible for policing the groceries supply code of practice, which was instituted under the last government in 2010 in order to ensure that the 10 biggest supermarket groups - with annual turnover of over £1bn each - did not abuse their relations with their suppliers.