Tesco has been on the receiving end of more than half of issues raised by suppliers with the new Groceries Code adjudicator in the last year.
The troubled supermarket was at the centre of 54 per cent of complaints made, with 11 per cent of Tesco's suppliers going to the new government ombudsman, according to a survey conducted by YouGov.
The next most-troublesome was Morrisons, which received 26 per cent of complaints, meaning six per cent of its suppliers had gone to adjudicator Christine Tacon. Then came Asda and the Co-operative, followed by Sainsbury's and Iceland.
Marks & Spencer, Waitrose and Lidl each had a small number of complaints – one per cent of the total – with only Aldi registering none.
In fact, 44 per cent of suppliers said the German discounter always complied with the code - compared with just four per cent of Tesco's suppliers.
Tesco has been at the centre of a storm around its handling of supplier relationships, which caused the company to overstate its profits by £263m, prompting a swathe of investigations both internal and external.
Most recently, the UK's auditing body the Financial Reporting Council put retailers' relationships with suppliers under the microscope in part because of Tesco's behaviour. While chief executive Dave Lewis has been busy turning the UK's biggest retailer around, it seems those crucial supplier relationships are still fraught.
But it was Iceland that came out worst: five per cent of its suppliers said it never complied with the code, while just six per cent said it was consistent in sticking with it.
But overall, there was a drop in the number of suppliers reporting issues in their dealing with the top 10 retailers in the last year, down from 79 per cent in 2014 to 70 per cent in the last 12 months.
“We still have some way to go in important areas but this is a clear sign we are on the right track. Suppliers are more aware of the GCA and its work and fewer now believe the GCA will not be able to do anything if they bring an issue to me”, said Tacon.
Tacon said her “collaborative” approach with the retailers was making a difference – although acknowledged an ongoing investigation had also had an impact.