Nisa’s sales to partnered stores increased by 1.1% to £1.5bn in 2019, according to Co-op’s newly-published interim report.

However, Co-op also revealed it had discovered £33m of accounting errors made by the Nisa finance team prior to Co-op’s takeover. 

This included a deficit of £20m related to tobacco stock picking errors in its warehouses, a £9m deficit in income from suppliers and a £4m banking error.

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The necessary readjustments wiped £10m off the group’s reported 2018 profits.

Better Retailing understands share payments to Nisa retailers are unaffected.

Despite the mistakes, Co-op lauded the Nisa deal for “increasing Co-op buying power”. 

Nisa chief executive Ken Towle revealed that more than 10% of all Nisa sales now come from Co-op-branded lines, helping the wholesaler achieve growth 1.4% stronger than the market average.

Co-op delays Gro summer expansion

Co-op also reported strong results in its food business, with like-for-like sales up by 1.9%.

However, the company failed in its target to open 100 stores in 2019, instead settling for 79 openings, 152 refits and 10 shop extensions. 

It said the coronavirus would add £200m to its costs for 2020, but added this would be offset by additional sales and tax relief. 

Find out more on our coronavirus information hub for retailers