LONDON, Jan 18 (Reuters) - British health officials are aiming to be ready to start charging Britons for COVID-19 tests that are currently free at the end of June, a document seen by Reuters shows, in what could be a risky gambit for the government. Britain has been increasingly dependent on rapid testing to try to tackle the more-transmissible Omicron variant, which has spread rapidly through the population but is less severe. The government has previously said it will end the universal free provision of easy-to-use lateral flow devices (LFDs) at a "later stage", with individuals and businesses bearing the cost. The Department of Health has declined to say what the tests cost, citing commercial contracts. One source has said they can run to 30 pounds ($40.75) for a pack of seven. The tests have freely available to order online or pick up from local pharmacies since April. The UK Health Security Agency said that between Dec. 30 and Jan. 5 more than 8 million LFDs were conducted, the highest weekly figure on record. The document seen by Reuters, which was shared between health agencies to prepare scenarios for the change, shows that the timetable for the switch has been pushed back from earlier in the year because of the arrival of the Omicron variant. That target could move again if the virus throws what one official close to the health service described as a "curve ball", perhaps in the form of another variant, which would mean the plans would again be postponed. Tackling the ongoing pandemic remains high on the political agenda in Britain, where Prime Minister Boris Johnson is under fire for attending an event in the garden of his Downing Street residence during a COVID-19 lockdown. He has apologised for attending, but an increasing number of reports of alcohol-fuelled gatherings at the heart of government have prompted calls for his resignation, including from some in his governing Conservative Party. read more The document says officials are now working on the premise that an online ordering system should be ready at the end of June to direct most people, excluding key workers and some others, to providers of paid-for LFDs in what is described as a "ramp down of the Universal Testing Offer". FREE AS LONG AS NECESSARY "We will continue to provide free tests as long as necessary. It is one of the most important lines of defence, alongside our vaccines programme," a government spokesman said when asked about the new date. "With cases remaining high, we continue to process millions of tests a day – more than any European country – providing a free LFD to anybody who needs one." Earlier this month, education minister Nadhim Zahawi said he did not recognise a report in the Sunday Times of plans to end the free mass supply of LFDs. read more Two sources told Reuters last year that the first plan was to have the infrastructure in place to start charging early this year, but that target was postponed when the Omicron wave hit Britain in late November. read more The document said there would be a "triage" system to direct people as to whether they were eligible or not for a free LFD. It acknowledged that some of those who expected to get a free test but could no longer get one would react "negatively". There was a possibility, the document said, that those people could try to game the system to access a free test. Britain has seen a drop in coronavirus cases and a fall in hospital admissions from recent highs, leading some in government to hope that so-called Plan B restrictions in place could be removed before the end of the month. S8N2R109L Iain Buchan, who led a trial of the tests in Liverpool, said Britain"s distinctive approach of making the rapid tests freely available for months, unlike many other countries, had been a success, and cautioned against introducing charges for tests. "Viruses move quicker than free market economics," Buchan, chair in Public Health and Clinical Informatics at the University of Liverpool, told Reuters. ($1 = 0.7363 pounds)