Aldi has become the latest retailer to drop Irish meat supplier Silvercrest Foods after tests found traces of horse DNA in its burgers.

The retailer today (31 January) said tests for horse DNA in frozen own-brand burgers supplied by Silvercrest proved negative in three samples. However, in three samples, traces of less than 1% were found.

As a result, Aldi said it has suspended its contract with Dalepak to supply beefburgers and is conducting further investigations at the factory. In tandem, Aldi Ireland has terminated its contract with Silvercrest due to what it says is a "breach of its contract in supplying beefburgers".

"Aldi UK's customers are our absolute priority," a spokesperson for the retailer said. "This is why we immediately withdrew these products until such a time that we could verify that there was no risk to our customers. We are deeply angry and feel let down by our supplier and we are pursuing more tests until we are certain that we understand how the production line was contaminated.

"Aldi requires rigorous verification and quality control procedures and we cannot allow our quality commitment to our customers to be compromised. We will continue to maintain active scrutiny across our supply lines, and we assure our customers their health and safety is our number one priority."

Yesterday, the Co-operative Group joined Tesco in "delisting" Silvercrest as a supplier. Tesco was one of a number of retailers found earlier this month to be selling beef burgers containing horse meat DNA.

The burgers were supplied by three plants in the UK and Ireland owned by meat processor ABP Food Group, including Silvercrest in Ireland.

The Silvercrest plant remains closed, ABP confirmed yesterday. It has introduced new DNA tests across its business and said it would audit all its suppliers.

At the weekend, Irish agriculture officials said the horse DNA had been traced back to raw material from Poland.

ABP said on Saturday it was "relieved" the source of contamination had been found. It added it had "never knowingly purchased or traded in equine product". The group has appointed a new management team at the Silvercrest plant and introduced its own new DNA tests.

ABP said today it "understood" Tesco's decision to no longer use Silvercrest as a supplier. "We have let our customers down in this incident and we apologise for this," it said. However, it declined to comment on The Co-op's move.