Hong Kong's two largest consumer retail chains have started rationing some food items and medicines to restrict panic purchases that were triggered in city over the past week amid fears of a lockdown as the daily count of fresh COVID-19 cases shot past the 50,000 mark.

According to a Reuters report, health authorities reported 52,523 new COVID-19 cases on Friday and 136 deaths. It was the third consecutive day that the number of cases topped 50,000.

The number has soared from a mere 100 infections in the beginning of February and a three-month period of zero cases that lasted till the end of December.

The spread has limited available manpower in the health care system, and for public transport, mall operators, supermarkets and pharmacies due to the large number of people having gone down with Covid.

Supermarket chain ParknShop announced limits of five items per customer on staples such as rice, canned food and toilet paper, while pharmacy Watsons put the same limits on medication for pain, fever and colds, the Reuters report said.

"Effective today, ParKnShoP and Watsons Hong Kong will impose purchase restrictions on selected products and medication at all stores," Watsons said in a statement.

Hong Kong officials have repeatedly asked people not to go in for panic buying this week, saying supplies were adequate.

Amid public complaints of confused official messaging, Hong Kong Chief Executive Carrie Lam has said her government had no plan for a "complete lockdown" while it plans compulsory testing of the city's 7.4 million residents.

The government would announce details of the plan when finalised, she said.

The surge in cases and fears of a lockdown have led to an exodus from the city, where authorities are clinging to a "dynamic zero" policy that seeks to eradicate all outbreaks at all costs.