Boris Johnson defends under-fire virus 'test and trace' scheme

British prime minister Boris Johnson on Wednesday (3) defended a new "test and trace" system designed to stop a second wave of coronavirus infection, amid criticism about a lack of transparency.

The scheme, launched in England last week to coincide with the easing of lockdown restrictions, uses an army of 25,000 tracers to contact people who may have been exposed to the virus.

Anybody thought to be at risk of infection will have to self-isolate for 14 days, even if they have no symptoms.

The government aims to be able to trace the contacts of 10,000 people a day.

"NHS (National Health Service) Test and Trace started operating a week ago," Johnson told a daily briefing on the government's response to the outbreak.

"And already thousands of people are isolating who wouldn't have been doing so before this service was introduced. They are thereby protecting others and reducing the spread of the virus."

Johnson gave no exact figure and critics claim the scheme's launch was rushed to divert attention from public outrage over his most senior aide's breach of lockdown restrictions.

Workers have also claimed they were not highly trained or were doing nothing.

The head of a cross-party parliamentary health committee piled fresh pressure on the government, criticising the system's head, Dido Harding, for failing to give appropriate data.

"I hope you understand that our frustration is that it is very hard to scrutinise what the government is doing if we're not given the data that allows us to do that," said Jeremy Hunt.

He said Harding had been given advance notice she would be asked to provide data, and was "disappointed" she could not give figures for how many people had been contacted so far.

Britain's government has come under sustained pressure for its response to the outbreak. The country has officially counted nearly 40,000 deaths -- the second-highest number in the world.

It has been criticised for failing to introduce tougher social distancing measures and lockdown earlier, and for a lack of widespread testing and provision of protective equipment.