Anti-terrorism legislation and a no-fly zone will be used to secure the Bilderberg Group's meeting at The Grove hotel.
Senior Hertfordshire police officers told Watford residents the measures were being used as a precaution as there was no intelligence about a specific threat.
However at a public meeting this evening officers also said the public had been kept in the dark about the event until recently due to fears it could become a terror target.
Watford Chief Inspector, Nick Caveney, said: "There is no information regarding a terrorism threat.
"However it must be recognised that there will be a number of high-profile people involved in going to this event and with previous terrorist events we have had not intel that something would happen.
"That was the reason it was not appropriate for us to be speaking and recognising publicly that the event was going on."
Officers also told residents at the meeting at Watford Town Hall they were confident Hertfordshire taxpayers would not have to shoulder the cost of the Bilderberg security operation.
Inspector Dave Rhodes confirmed the Bilderberg Group had made a donation to the policing cost of its forthcoming three-day conference at The Grove Hotel.
Yet officers declined to divulge the exact amount, saying it would be available through the Freedom of Information Act after the event.
Chief Inspector Rhodes said: "I am confident the operation will be cost neutral for the taxpayers of Hertfordshire. A donation has been made by the organisers of the conference.
"That is a private amount not to be disclosed at this stage. We don't know how much the operation will cost at this stage."
His comments came as Hertfordshire Constabulary moved to allay fears of residents in about the impact of the Bilderberg Group's meeting, which starts on Thursday, and the protests it is likely to attract.
The Bilderberg Group has been meeting secretly every year since 1954 and draws leading politicians, businessmen as well as journalists and academics to discuss pressing geo-political issues of the day.
In recent years its meetings have attracted a growing number of demonstrators who see its activities as a threat to open democracy.
At this year's meeting UK figures such as chancellor George Osborne, shadow chancellor Ed Balls and cabinet minister Ken Clarke are set to spend three days with representatives from mulit-national corporations such as Goldman Sachs, Amazon and Google.
At today's meeting police played down reports that the number of protesters converging on Watford could be in the hundreds or thousands.
Chief Inspector Rhodes said reports from the constabulary's US counterparts at Fairfax County Police, who had overseen last year's Bilderberg protest in Chantilly, Virginia, indicated fewer than 100 protesters had come from outside the area.
He said most demonstrators appeared to have come locally and been motivated by an anti-cut and anti-austerity agenda.
At the meeting, local politicians and residents of old Hempstead Road voiced displeasure that they had only recently learned that their road was set to be used for parking for Bilderberg demonstrators.
They were assured by police that the main protest would take place in the designated area in the grounds of The Grove.
The attendees also heard from Bilderberg protest organisers. Hannah Borno, a journalist involved with organising the Bilderberg Fringe Festival, told the meeting she had attended previous protests and they had been safe, peaceful affairs.
She added: "It is about transparency. They have released the list today and Ken Clarke, George Osborne and Ed Balls will be with Peter Sutherland of Goldman Sachs and the vice chairman of Barclays and HSBC in a luxury hotel for three days.
"We want our politics to be disentangled from business".