There could "potentially" be more members of the Manchester attack terror network at large, home secretary Amber Rudd confirmed this morning, while also revealing temporary exclusion orders have been used for the first time.
"It's an ongoing operation. There are 11 people in custody; the operation is still really at full tilt, in a way," she told the Andrew Marr show.
"Until the operation is complete we can't be entirely sure that it is closed," Rudd said.
Rudd also said that the government has started to use temporary exclusion orders (TEOs) for the first time; until recently, zero had been issued. Rudd would not disclose the number that have now been issued.
Introduced by David Cameron during his tenure as Prime Minister, the TEOs are meant to disrupt and control the return to the UK of British citizens who have engaged in terrorism-related activity abroad.
The UK's top counter-terrorism officer Mark Rowley said earlier this week that police have made "significant arrests and finds" in their inquiry into the bombing at Manchester Arena last Monday, which killed 22 people. Many others are still in hospital.
Yesterday, it was announced that the UK's threat level had been reduced from "critical" to "severe". Intelligence officials judged another attack on British soil had diminished, with troops to be withdrawn from public guard posts at the end of the bank holiday.
Prime Minister Theresa May said that the Joint Terrorism Analysis Centre (Jtac) decided yesterday morning to reduce its public assessment of the likelihood of a follow-up attack from the Manchester bombing on Monday.
From midnight on Monday onwards members of the armed forces will be "gradually withdrawn" from postings at civilian events, May said.
Police have also issued CCTV stills of Salman Abedi, the Manchester bomber, in a plea for information about his movements between the 18 May and the attack four days later.
Today, Andrew Marr asked Rudd about Abedi being a former subject of interest to MI5.
"The intelligence services are still collecting information about him and about the people around him. But I would not rush to conclusions, as you seem to be, that they have somehow missed something," she said.
The home secretary confirmed that currently MI5 are looking at 500 different plots, with 3,000 people on a top tier list and 20,000 on a lesser high risk list.