MI5 admits for the first time that it made a mistake in failing to track the 2017 Manchester bomber, MPs have said.

A report by the Intelligence and Security Committee said MI5 had recognised it had moved “too slowly” to establish how dangerous Salman Abedi, 22, really was.

The security service had cause to monitor Abedi’s return to the UK from Libya days before the attack on Manchester Arena, the report said. Twenty-two people died in the attack.

In wide-ranging criticisms, the committee said the government had also failed to fully learn lessons from attacks dating back 13 years.

Abedi is believed to have been taught bomb-making while in Libya, before returning to Manchester in May last year to construct his device. He walked into the Manchester Arena, where thousands had been watching US singer Ariana Grande perform, and blew himself up.

A previous report into the attack revealed that MI5 had planned to review the risks posed by Abedi – but the meeting was not scheduled to take place before the attack occurred.

In its findings, the ISC said there had been “no follow-up action” after Abedi went to prison to visit a jailed terrorist organiser from Manchester.

Furthermore, MI5 could have put a plan in place to monitor Abedi’s movements, which would have revealed his return to the UK from Libya, days before he struck. “MI5 have since admitted that given the information they had on Abedi, they should have done so,” said the committee. “Abedi had been flagged for review but MI5’s systems moved too slowly.”

The committee said one failing it had identified was so sensitive it could not be shared publicly. But it added: “What we can say is that there were a number of a failings in the handling of Salman Abedi’s case. “While it is impossible to say whether these would have prevented the devastating attack on 22 May, we have concluded that as a result of the failings, potential opportunities to prevent it were missed.” In their highly-critical report, MPs and peers on the committee also found:

Measures to control access to chemicals needed for bomb-making were “hopelessly out of date”

Communication companies were still failing to meet their social duties to detect terror planning online – and it recommended putting pressure on them by targeting their profits

There had also been “fundamental failings” by the Home Office, police and Surrey County Council over their handling of the teenager who placed a bomb on the London Underground in September 2017

MI5 should rethink how it “joins the dots” on some suspects because it had failed to appreciate the potential dangers posed by Khalid Masood, the