Police say five men arrested near a UK air base at the weekend are suspected of preparing a terrorist act.
The men are all British citizens from London and aged in their 20s.
Counter-terrorism police say they need "space" to investigate the incident "carefully and clearly".
Five men arrested near a military base in England early Sunday are all British citizens from London, authorities have confirmed, amid claims Iran's government was attempting to attack the facility.
Despite counter-terrorism police giving an update into their investigations on Monday, information surrounding the arrests remains confusing.
In a statement, police said the men had been arrested on suspicion of preparing a terrorist act, and committing explosives offences.
The complex at the centre of the probe is RAF Fairford, an air force base about 140 kilometres west of London which the US military has used to launch strikes Iran this year.
The arrests have preceded concern not just in the local village community — who were evacuated at the weekend — but the United Kingdom more broadly and across the Atlantic, where US politicians have been quick to point the finger at the Islamic Republic.
Florida Congresswoman Kat Cammack said, without providing specifics, Iran was "clearly involved" in a plan to attack the base, and US President Donald Trump claimed the arrested men had been under investigation "for a long time".
However, local residents maintain they were the ones to raise the alarm, after spotting several vehicles in the area surrounding the base early Sunday.
"I am very aware of the levels of speculation about the motivation behind this incident, and the geopolitical questions that are being raised," Deputy Assistant Commissioner Vicki Evans, who coordinates counter-terrorism policing in the UK, said in a statement on Monday.
She said officers had several new lines of inquiry and needed "space to work carefully and clearly".
"This is a hugely complex and large-scale operation, involving local and national policing, the Ministry of Defence, and local agencies, who are working together to progress the investigation and support for the community," she said.
The five men arrested are all British citizens from London, police confirmed, and aged between 23 and 25. They all remain in custody, although no charges have been laid.
While less common in Australia, UK police routinely announce the nationality and ethnicity of suspects in high-profile investigations to counter disinformation that can spread online, which has previously led to public disorder.
People who live near RAF Fairford have told British media security was ramped up around the base in the days leading up to the arrests.
One resident claimed to the BBC they had been walking near the military facility in the hours before the incident took place and encountered a police officer who instructed them to return home and stay inside.
A local farmer has also said they were the ones to alert authorities, after spotting eight to 10 hooded men in the area before 1am on Sunday.
"When they saw me they ran ahead of me. Some into the field and some towards the neighbouring village," she said.
"I then realised that something highly unusual was taking place."
UK Defence Secretary Wes Streeting on Monday thanked the farmer but said they only had "a partial picture" of the situation.
Police have previously confirmed they are investigating whether Iran could have been involved.
"We know they hate our democracy," Mr Streeting said.
On Monday, Iran's embassy in London released a statement in which it "categorically rejected" allegations the country was involved in the incident.
However, earlier this year, the Iranian Revolutionary Guard Corps (IRGC), a paramilitary force which reports directly to Tehran's supreme leader, asserted RAF Fairford would be a wartime target, given the US had launched strikes from there.
The IRGC has been designated a terrorist organisation in Australia and the UK.