The big four supermarkets dominate the grocery market

The measure is likely to be among the Competition Commission's suggestions to remedy problems it has identified in the UK's grocery market.

There could also be a call for an ombudsman to protect food suppliers in any disputes with the big four supermarket chains.

The regulator will release its latest report at 1630 GMT.

In its initial report in October, the commission said it was concerned about retailers being able to transfer unexpected costs to their suppliers.

The net effect may be viewed as reinforcing a status quo in which Tesco has double the market share of its nearest rivals Robert Peston, Business editor, BBC News Read Robert Peston's blog Send us your comments

One solution may be to create a supermarkets ombudsman to protect suppliers in their dealings with the big chains, but there has been some doubt about how effective a measure that would be.

"The Competition Commission needs to be seen to be doing something and this could be a sop to suppliers," said Julian Wild from Rollitts Solicitors, who represents food companies in their dealings with supermarkets.

"It's hard to see that it's going to have a major impact," he added.

'Too few supermarkets'

According to market research group TNS Worldpanel, the UK's big four - Tesco, Asda, Sainsbury's and Morrisons - now account for more than three-quarters (76.2%) of the grocery market.

In October, the commission concluded that there were aspects of the grocery market that prevented or restricted competition.

A LONG INVESTIGATION March 2005 - OFT finds supermarkets are sticking to their code of practice November 2005 - Competition Appeal Tribunal tells OFT to reconsider March 2006 - OFT begins consultation May 2006 - OFT refers grocery market to Competition Commission October 2007 - OFT publishes preliminary report February 2008 - Competition Commission publishes provisional recommendations May 2008 - Deadline for final report

It said many people had too few large supermarkets to choose from in their local area which acted as a barrier to competition

The commission found, for example, that certain retailers hold on to land, which could prevent others from setting up shop nearby.

The commission is expected to recommend changes to the planning system to combat this problem.

These could involve a limit on the length of time supermarkets can keep undeveloped land and stopping supermarkets from imposing restrictive covenants on land to prevent competitors building on it.

Retailers could even be forced to sell stores or land in areas where they are too powerful.