Ministers were not told about the presence of the potentially deadly legionella bacteria on the Bibby Stockholm barge until Thursday night, the health secretary has said, three days after health protection officials informed the county council. Steve Barclay said he could not say whether Dorset council had informed Home Office officials earlier about the test results on the vessel, which is being used to house asylum seekers, but that ministers first knew late on Thursday. His comments came as Jenny Harries, the head of the UK Health Security Agency (UKHSA), which carried out the tests, confirmed the results had been passed to the council on Monday, a week ago. The first asylum seekers were moved on to the barge that day, only for all 39 to be taken off on Thursday and Friday. Asked about the timetable, Barclay told Sky News that the tests for legionella, which can cause legionnaires’ disease, a severe type of pneumonia, if small droplets of water containing the bacteria are inhaled, were “a standard thing”. “The Home Office did take precautionary measures as soon as we got the results. Ministers found out on Thursday night is my understanding,” he said. “It’s perfectly normal that these tests are done. They were done at the end of the month. Once ministers were aware that there were some concerns they took precautionary measures. The barge will then be made ready and people will come back.” Asked why Dorset council had said it told the Home Office on Monday, the day the test results arrived, Barclay said: “It may be the council notified the Home Office. That’s an issue for those in the Home Office to respond to. “My understanding from colleagues in the Home Office is that it was notified to Home Office ministers on Thursday, and they then took very quick action as a result.” Speaking to BBC Radio 4’s Today programme, Harries confirmed that the presence of legionella on the 90 metre-long barge, which is intended to hold up to 500 asylum seekers while their claims are processed, was confirmed to the council on Monday. Because it was detected in a structure rather than in a person, it was for the council to lead on, she said. “I think it’s really important to recognise if this was a human detection, then that is very definitely a UKHSA responsibility to act. “In this case, environmental health officers lead on that, and it’s really important that they do because in an environmental sample, you need to understand how and when the sample is taken.” Such a routine test result would not normally mean she would be informed, Harries said, and she was only informed on Thursday. “Our local health protection teams were alerted out of hours overnight on the Wednesday, and I was alerted the next morning,” she said. “Then we’ve obviously jumped in immediately, put in an incident management team and support those who regulate these affairs to make sure that all the right precautions for human health were present. “This is quite a common finding, and it’s quite complex. Just finding legionella does not necessarily mean there is a significant risk to human health and it is primarily the responsibility of the operator or the manager of the premises or the services to ensure that that is fully managed.” Dorset council confirmed to the Guardian on Sunday evening that it had raised the alarm about legionella with the Home Office contractors on the same day it received the test results. It is unclear when the contractors told the Home Office about the results. Carralyn Parkes, a Portland councillor who is pursuing legal action against the Home Office about the barge in a personal capacity, questioned the delay in evacuating people. “The legionella test results came back on Monday. Why were the asylum seekers not moved off the barge immediately? It’s all a bit chaotic. Hasty decisions have put people on the barge at risk.” The Labour leader, Keir Starmer, meanwhile made an implicit admission that his party would continue to use facilities such as the Bibby Stockholm if it won the next election. Asked whether Labour would keep using the barge if it won power, he said: “I don’t want to keep barges or hotels or airfields, for that matter.” But he added: “We’re going to inherit a very difficult situation and so we’re going to have to manage as best we can.”