The arrests, including three on suspicion of conspiracy to commit murder, follow an investigation by Counter Terrorism Policing (CTP) London in connection to the event at Shrubland Hall at the weekend (9-12 July).
Organisers of the UK Ijtima event were advised to close slightly earlier than planned as a precaution due to the “potential serious threat” and all 15,000 attendees left safely, police said.
The people arrested included a 27-year-old man in Ipswich, a 35-year-old man in Greater Manchester, two 42-year-old men in Essex and five men in Surrey, aged 27, 29, 55, 60 and 82, on 12 July.
In addition, a 33-year-old man in southeast London and a 31-year-old man and a 48-year-old woman in east London were arrested on 13 July.
Eight of the men were arrested and detained under section 41 of the Terrorism Act 2000 and remain in police custody.
Three of the men, the 82-year-old, the 55-year-old and the 60-year-old, were arrested on suspicion of conspiracy to commit murder. The 82-year-old man has since been released on bail.
The woman was arrested on suspicion of assisting an offender.
Home Secretary Shabana Mahmood said the response of the police in tackling a “credible threat” to the UK Ijtima festival had “undoubtedly saved lives”.
“I know this is deeply concerning news for British Muslims,” she said.
“We must stand against hatred and we must unite around our shared belief in a country that is open, generous and tolerant to all our communities.”
Commander Helen Flanagan, head of CTP London, said: “After becoming aware of a potential serious threat towards the Islamic event in Suffolk, we have moved extremely quickly to make a number of arrests in various locations across the country.
She added: “I know this news may be concerning to the public and particularly those in the Muslim community, given that we believe the intended target was an Islamic event. But as we have shown, we will not hesitate to act if there is any potential threat, no matter who or what the potential target may be.
“Sadly, this activity is a stark reminder that the threat level in the UK is at ‘severe’, so we urge the public to remain vigilant and report anything if it doesn’t look or feel right.”
Read more from Sky News:
‘Nothing to suggest’ Ann Widdecombe murder political
Human trials of new Ebola vaccine set to begin in UK
Police are carrying out several searches across the country linked to the arrests.
Assistant Chief Constable Alice Scott from Suffolk Constabulary, which is supporting the operation, said: “We understand that the arrests and the context behind them may well cause some concern amongst our local communities.
She added: “The situation was declared a major incident early on Sunday morning with a multi-agency response convened to ensure a safe and properly co-ordinated departure from the event of the 15,000 attendees. The major incident status was withdrawn earlier today.
“This was a complex and fast moving scenario with the priority of all the agencies working together to ensure the safety of all the attendees.”
This breaking news story is being updated and more details will be published shortly.
Please refresh the page for the fullest version.
You can receive Breaking News alerts on a smartphone or tablet via the Sky News App. You can also follow @SkyNews on X or subscribe to our YouTube channel to keep up with the latest news.
