Manufacturers have warned that FSA plans to measure their progress on salt reduction in processed foods are fraught with difficulties.

The FSA's preferred approach to analysing data against targets agreed with industry is to take averages across categories.

British Meat Processors Association director Maurice McCartney said: "It would be a huge exercise. It would also be necessary to apply volume weighting when products sell in greater quantities than others."

Another industry source said some brand suppliers that had gone to great lengths to cut salt might not favour a category average approach. "For example, Heinz might prefer that the FSA took an average across the Heinz range, rather than across, say, baked beans."

Dairy UK technical director Ed Komorowski said such an approach would depend on companies' willingness to release data.

The FSA may also produce separate reports for retailers in a bid to assess their actions on salt cuts.