The Home Office has said it has "full confidence" in security for the Olympics, after reports of concerns from the United States.
The Guardian claimed the US was furious about security plans and wanted to send up to 1,000 of its own people, including 500 FBI agents.
The deployment of overseas security officers at the Olympics has become standard procedure in recent years.
But final responsibility for security rests with the host government.
The Home Office say security planning is on track, funding has been protected, and the government is committed to delivering a safe and secure games.
Officials also said they "don't recognise as true" that concerns have been expressed at an official level from the US side.
The Guardian article says the London riots, the arrest of a security guard at the Olympic site and arrests before the visit of the Pope last year have raised US anxieties.
The restriction of the scope of anti-terrorism stop-and-search powers is claimed to be one of the reasons for concern.
Responding to claims in the article, the games organisers Locog said precise numbers of security officers are only now being finalised because the venues themselves have only just been completed.
Earlier this year National Olympic security co-ordinator Chris Allison said he believed 12,000 officers would be needed nationally to police the event.
He said another 10,000-15,000 security officials could also be deployed by private security firm G4S.
'Safe and secure'
But it is thought there is a "gap" of around 5,000 staff in the plan for security of all the Olympic venues.
They would be carrying out bag and vehicle searches and perimeter security.
It is understood the Army has offered to fill the gap but the sticking point is who pays for it and there are understood to be ongoing talks between Locog, the military and the Metropolitan Police.
A Home Office spokesman said: "Security planning is on track and funding has been protected. The government is committed to delivering a safe and secure Games that London, the UK and the world can enjoy.
"The International Olympic Committee (IOC) undertake detailed inspections of security preparations and have full confidence in our plans. The UK has a strong and close working relationship with the US, who have expressed similar confidence."
The US Embassy has declined to comment.
The BBC's security correspondent Gordon Corera said: "The US is understood to be taking a close interest in the plans and is intending to send over hundreds of personnel to protect its athletes."