LONDON (AP) — The British government’s new online system for “essential workers” and their families to book appointments for coronavirus tests got off to an inauspicious start Friday.

Barely three hours after launching, the link stopped accepting applications for the day following “exceptional demand” and said more tests, both for drive-through sites and home delivery, will be made available Saturday.

Clicking on the link, aspiring applicants were greeted with the brief message: “Coronavirus test: capacity reached for today.”

In a tweet, the Department of Health and Social Care apologized for any inconvenience caused and said it is “continuing to rapidly increase availability."

The self-referral site is a key element of the government's plan to meet a target of 100,000 tests a day by the end of the month, and will likely play a big role in how lockdown restrictions, which are due to last till at least May 7, are lifted.

For now, changes to the lockdown are not being considered given that the U.K.'s coronavirus-related death toll in hospitals is fast approaching 20,000 .

Prime Minister Boris Johnson's office said that within two minutes of the portal's opening, 5,000 home-testing kits had been ordered — the day's available capacity — and that another 15,000 testing slots at drive-through sites had also been snapped up. It said more tests will be made available over coming days, with an aim of 18,000 home tests available to be booked each day by next week. The goal is for them to arrive the next working day, with results sent back within 72 hours.

On Thursday, following weeks of criticism of the government's testing program, Health Secretary Matt Hancock announced a step-change in its strategy — essential workers and their families could go online to make a self-referral if they show coronavirus-like symptoms.

In addition to those working directly in the National Health Service and in care homes, the swab tests are available to others, such as prison workers, teachers, food-delivery drivers and journalists covering the coronavirus pandemic. Around 10 million people could potentially receive a test under the expanded criteria.

Government figures Friday showed that the government has made headway but that it's still well short of target with just six days to go. They showed that in the last day before the self-referral site was launched, the number of daily tests increased by around 5,000 to 28,532.

The NHS is also moving closer to rolling out a smartphone contact-tracing app aimed at managing infections after the lockdown is eased. Its digital transformation arm said it plans to launch the app “in the coming weeks.”

The app will measure how close users come to other devices using Bluetooth and keep an anonymous log of the data on the phone. It will also advise users what to do if they come close to someone with symptoms.

The British government also said another 684 people with the coronavirus have died in U.K. hospitals, taking the total to 19,506, compared to the 616 deaths recorded in the previous 24-hour period.

The U.K.’s death toll is the fourth highest in Europe, behind those of Italy, Spain and France, each of which has reported more than 20,000 deaths in hospital.

There has been increasing scrutiny of the U.K. figures in recent days for dramatically understating the actual number of coronavirus-related deaths, as they don’t include those who have died in care homes or elsewhere in the community.

Jill Lawless and Kelvin Chan in London contributed to this report.

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