Three samples of locally made ice cream that used milk powder from New Zealand and whey mist from Ukraine - under the Daqiaodao brand, tested positive for COVID-19 on Thursday in Tianjin.

The city has launched a campaign to close down cold storage houses related to the ice cream since then. The company said it had produced 4,836 boxes, and 1,812 had been sold to various provinces.

So far, a total of 2,089 boxes of the ice cream had been sealed up. Each box contains six ice cream products, each of which having a net weight of 450 grams. Most of the 935 boxes entering the local market have not sold out, it said.

Tianjin is now examining a total of 65 boxes that had been sold in the local market. On Thursday evening, it asked residents who bought the popular treat to report their health and physical movements.

The city has notified the market regulation authorities in the provinces where the ice cream was sent so it can be traced.