he Liverpool hospital bomber was believed to be a lone wolf who spent weeks or even months preparing his attack after learning bomb-making techniques online, it has emerged.

They said he was also believed to have acted alone and to have gained both his inspiration and the techniques required to assemble an explosive device on the internet, allowing him to escape detection.

But the sources also admitted that his precise motivation — particularly whether he was inspired by Islamist ideology — and exactly when he began preparing remained a mystery and could take weeks to establish as his phone and computer records are examined for evidence.

His intended target is also still to be established conclusively, although police have said that he asked to go to the hospital, rather than the nearby remembrance service at Liverpool’s Anglican Cathedral, and officials suggest that it would be odd to go the hospital if an attack on the service had been his ambition. The disclosure follows the release on Monday of four other people held after the attack in which Al Swealmeen, an asylum seeker who is believed to be of Iraqi and Syrian heritage, died when the cab he was travelling in blew up minutes before 11am on Sunday.

The driver, David Perry, managed to escape moments later before the vehicle burst into flames and became a charred wreck.

On Tuesday ministers warned of the danger of further attacks by bedroom radicals. Damian Hinds said police were making new discoveries about the plot by the hour but that “it could be weeks before the full picture is known of how this came about, the motivation, were there other people involved and so on”.

The security minister warned, however, that “periodically atrocities will happen” and that bedroom radicalisation — which become a heightened risk during the coronavirus lockdowns — was a likely factor in the attack.

“We use the term lone wolf a lot,” he said. “Sometimes it can be a little misleading but it certainly is true that we have seen a shift from directed attacks, part of a bigger organisation, where people are following instructions, sometimes quite complex organisation, and moved from that to more self-directed,…