Suppliers and industry bodies were left exasperated this week as the major supermarkets demanded a review of the Grocery Suppliers Code of Practice before the Adjudicator is even appointed.

The calls came during the first session of pre-legislative scrutiny by a BIS ­select committee over the draft bill for the Groceries Code Adjudicator.

A Sainsbury's spokesman said a review would be "worthwhile" and suggested that the government let the GSCOP "bed down ­before going through the ­bureaucracy of a new ­adjudicator".

A review would be "very sensible," a spokesman for Asda added, as there has been "no evaluation of how effective GSCOP has been".

But a spokeswoman for Traidcraft slammed the demand as an "obvious and irresponsible attempt to further delay setting up the much-needed GCA. Every day that passes without a GCA is another day when suppliers are squeezed by retailers with no route to recourse."

The ACS described the move as "yet another delaying tactic", and urged the government to push the bill through quickly.

And the NFU complained the watchdog "has been ­delayed enough. We need to get it up and running."

Of the mults, only Waitrose are not calling for a further review of the code.

Meanwhile, MPs on the Environment, Food and Rural Affairs Committee recommended that the GCA was given the power to carry out "pro-active ­investigations" and can "impose financial penalties as soon as it is established."