Attendants will have to curb the petty habit of ticketing motorists who have overstayed by a minute, or whose wheels stray just an inch over the line.

Ministers facing local elections next month have finally awoken to the fact that many motorists are infuriated by the behaviour of wardens who are under pressure to extract maximum revenue from drivers.

Alistair Darling, the transport secretary, has written to MPs admitting that many motorists’ complaints about the way they are treated “may be merited”.

A transport department memo sent to members of the Commons transport select committee accuses local authorities of employing wardens without proper training and allowing staff to reject valid appeals against fines. It also calls for an end to “confusing” and “incomprehensible” parking restriction signs.

The committee is investigating parking enforcement across England amid a backlash against the behaviour of some wardens as recent figures show fines in 2003-04 surging past £1 billion for the first time.

Complaints include wardens issuing tickets without stating the date or even the street where offences are supposed to have occurred and slapping tickets on cars while their owners are trying to find a functioning pay machine.

In Birmingham city centre, £60 fines were issued after council staff painted yellow lines around vehicles while they were parked. In Newcastle, wardens last year issued almost £200,000 of tickets in the five streets surrounding the Royal Victoria Infirmary, while on the streets around Manchester Royal Infirmary the figure was over £180,000, from 3,000 tickets.

Wardens have become so zealous in some areas that many are attacked by enraged drivers. In Newham, east London, wardens have been given police protection after 21 attacks in 13 months. Their colleagues in Havering, a nearby borough, have been issued with stab-proof vests to protect them from irate motorists.

In a 20-page submission to the committee, the Department for Transport says that it is recommending a softer approach to parking enforcement and is drawing up new statutory guidelines.

Among the parking practices they have identified are penalty charge notices slapped on cars where disabled badges are displayed upside down and blanket ticketing of cars in bad weather when yellow lines are obscured by snow.

The £1 billion collected in parking fines generates a surplus of £439m after costs. By law, councils are supposed to plough the money into improving transport systems.

However, the document admits there is “not much information” about what happens to the extra cash, leading to public suspicion that “authorities are only in it for the money”.