HONG KONG • Hong Kong reported the lowest number of new Covid-19 cases yesterday since its latest - and worst ever - outbreak started last month, bolstering hopes that stringent city-wide containment measures can be eased.

The city has also seen a decline in the share of cases with unknown origins over the past week, signalling that untraceable infections are dwindling. It reported 23 new local virus cases yesterday, of which only eight had untraceable origins.

For the past six days, cases of unknown origins have not crossed the 35 per cent mark, down from the peak of about 60 per cent in mid-July when the virus were quietly spreading in the community. More than two-thirds of Hong Kong's over 4,500 reported cases have emerged since last month.

Declining new local cases in Hong Kong as well as a falling proportion of untraceable cases underscore the success of recent social distancing measures in slowing transmission. New overall infections have dropped to fewer than 100 local cases for over two weeks.

Unknown infections, where patients cannot be linked to other confirmed cases, indicate hidden chains of transmission and have been a cause of worry. A high proportion of such cases forces public health authorities to take blunt and broad action such as shutting down entire cities as they race to stamp out the stealthy novel pathogen.

Despite the recent signs of relief, the Hong Kong government is projecting caution.

"There is no room for complacency in epidemic control," a spokesman for the Food and Health Bureau said in a statement on Monday, warning that the third wave of infections is declining much slower than the second, despite more stringent border and social distancing controls.

BLOOMBERG