UPDATE 2-Only 14% of England COVID-19 tests come back in 24 hours, in sharp drop as system buckles

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LONDON, Sept 17 (Reuters) - Only 14% of coronavirus test results in England came back within 24 hours last week, a sharp fall from the week before, according to data on Thursday that adds to pressure on a government fending off criticism that its strategy is collapsing.

The British government has been under intense pressure over the buckling of its promised "world-beating" system to test and trace coronavirus cases, meant to protect the country from a second wave of infection as schools reopened this month.

Government ministers have acknowledged that families are unable to get tests or being offered them only at remote locations. The new data, revealed on Thursday, showed that the arrival of test results has also sharply slowed.

The NHS Test and Trace scheme said there had been a 167% increase in the number of new people testing positive for COVID-19 in England since the end of August.

Only 14.3% of test results from all sites were received within 24 hours, compared to 32% the previous week.

For tests taken in person at sites around England, rather than on samples collected off-site, only a third were returned within 24 hours, compared to two-thirds in the previous week.

Prime Minister Boris Johnson acknowledged on Wednesday that there was not enough testing capacity, and said that he is aiming for the capacity to do 500,000 daily tests by the end of October.

The Test and Trace scheme reported that said positive cases had been rising since the start of July and are now double the number recorded when the system was launched in May. (Reporting by Alistair Smout Editing by Kate Holton and Peter Graff)