Confidential government documents obtained by Building reveal that the list of permitted offences include "b*****y with an animal or a person, assault and causing bodily harm by wanton or furious driving and battery".
In a letter to contractors and union representatives, the Department for Transport explained why some offences had been removed from the criminal record checks.
The letter said: "The department has decided that on balance, lesser 'offences against the person' – sex offences that only occur in very specific circumstances (and are rare) – should be removed from the list of disqualifying offences."
However, the government has compiled a long list of offences that will lead to a worker being prohibited from restricted areas. These include fraud and criminal damage.
A spokesperson for the Department for Transport said the list of convictions had been compiled to hinder terrorist activity. The spokesperson said that the offences related to acts of dishonesty or workers with a propensity for violence.
The security rules come into effect from next month. They apply to all workers on all airport projects.
On balance, sex offences should be removed from the list
Department for Transport
Unions have expressed disquiet about the legislation and fear that the security laws will reduce workers' rights. There is no appeal procedure.
Contractors also have concerns as it could mean that many workers will have to leave projects.
In the letter to contractors and union representatives, the Department for Transport said that it had carefully considered representation from both employers and trade unions on the range of the convictions that would lead to workers being prohibited from airport sites.
The letter said that the government was unable to accept that every conviction listed by the unions should be removed.
The Department for Transport letter said: "In order to achieve the objective of hindering terrorist activity by disqualifying individuals or by removing linkages to crime, the list needs to comprise offences that suggest that an individual has a propensity to violent acts or to behave in a dishonest manner or to abuse the trust placed in him."
Crackdown: The government’s airport security measures
Contractors at airport and port projects are only permitted to employ workers who can prove that they have at least five years of continuous employment. The directive is an attempt by the government to counter the perceived threat of a terrorist attack. It comes into force on 31 July.
Construction workers will from next month have to prove that they do not have a criminal record before they can work in restricted areas at airports. It stipulates that all recruits must disclose any criminal convictions not deemed spent under the 1974 Rehabilitation of Offenders Act. A security check will be carried out on all workers.