Freedom of Information responses revealed that there were now 2,617 people licensed under the Community Safety Accreditation Schemes introduced by Labour - a rise of 1,000 in three years.
The officials have as little as five days' training but there are concerns they may now have powers to dish out penalty notices for offences that could wreck people's careers, a newspaper reported.
They include park wardens, other council officials and shopping centre staff, who are allowed to give fines of up to £80 for offences such as littering and criminal damage. Their numbers rose steeply under former Home Secretary Jacqui Smith.
Under the schemes, they do not answer to a constable, and four out of five forces do not keep track on them once they have been given their powers.
A study by the Manifesto Club, a campaign group that opposes over-regulation, has found that such powers are being extended.
Examples include private security guards being allowed to hand out penalty notices for causing "harassment, alarm and distress".
It is an offence considered so serious that it may be recorded on the Police National Computer and come up in enhanced Criminal Records Bureau checks - potentially wrecking people's careers by debarring them from jobs such as teaching and nursing.
Conservative MP Dominic Raab told the Daily Mail: "These findings highlight the creeping expansion of law enforcement powers without proper accountability.
"The public expect spot fines and other police powers to be exercised by trained officers, who can be brought to book if they misuse those powers.
"Extending them to jobsworth officials and private contractors invites arbitrary abuse that risks undermining public trust."
The scheme, introduced by the Police Reform Act 2002, means that a chief constable can give employees of a range of organisations powers to carry out specific, approved roles.
In its report, the Manifesto Club said: "There is a danger of accredited organisations becoming a shadow police force, outside of both police control and public scrutiny."
The Home Office said the scheme "assists police in keeping communities safe", adding: "Powers are limited to dealing with low-level crime, individuals are vetted and training is approved by the relevant force."
