LONDON (REUTERS) - Eight mobile coronavirus testing units staffed by the army are starting to travel around Britain, with dozens more to follow, to help the government approach its target of 100,000 tests a day for the new coronavirus.

Health Secretary Matt Hancock has promised that number of daily tests by April 30, but by Friday (April 24), only 28,760 had been achieved.

Refitted vehicles will collect throat swabs, which will be sent to laboratories for processing, the Department of Health said in a statement on Sunday.

A further 96 of the units will start operating in May.

The units can be set up in under 20 minutes and will carry out tests on essential staff such as those who work in care homes, the police and prisons, and have found it difficult to travel to fixed, drive-through test centres.

There are concerns that a lack of testing could slow Britain's gradual exit from lockdown and delay the revival of its economy, the world's fifth-largest.

The mobile units carried out a trial run last week in Salisbury, Southport and Teesside. In Northern Ireland, the units will be staffed by contractors, not the army, the statement said.