The restrictions are among new guidelines for difficult deportation cases disclosed yesterday by Michael Howard, the Home Secretary, following a joint police and immigration service review in the wake of Mrs Gardner's death last August.
Although Mr Howard admitted 'lessons should be learnt', critics said the report was a missed opportunity to reform 'inhumane' deportation procedures.
Mrs Gardner, 40, died in hospital after a struggle with Metropolitan Police Deportation Squad officers and immigration officials at her home in Hornsey, north London; they were trying to return her to Jamaica. The force immediately suspended the three officers involved and halted the work of the squad.
The report gives the first official description of the body belt and gag used on her. Although their use has been governed by Metropolitan Police instructions since 1983, it has only now sought medical advice which said the gag was unsafe.
The instructions specify restraints can be used only on board aircraft and with pilots' consent, suggesting their deployment at Mrs Gardner's home was unauthorised. In the past two years, the belt was used in 37 out of 139 cases and the gag in six of those; the report does not indicate how many times they were used when the deportee was first detained. The review describes the gag as 'standard pharmaceutical tape two inches wide which could be twisted into a soft narrow rope-like strand to provide a mouth restraint where necessary.'
The inquiry into Mrs Gardner's death being conducted by the Police Complaints Authority and Essex Police is understood to be investigating suggestions that in her case, the tape was wound around her head 'several times', thus obstructing her breathing.
Five pathologists - for the Gardner family, the officers, and the inquiry, plus two consultant neuro- pathologists - have agreed that Mrs Gardner died from oxygen starvation for which the gag appeared to be the only possible cause.
The report is due to be completed within the next few weeks; the Crown Prosecution Service will decide whether the officers will be prosecuted. The review recommends that body restraints only be used in aircraft or in the period immediately before boarding, 'save in the most exceptional circumstances' that deportees facing restraint are medically examined and officers are better trained.
Research is under way on improving the design of the body restraints - a wide leather waist belt with handcuffs and leather belts for the legs - and whether an alternative is possible to the gag, to prevent deportees spitting and biting. Other recommendations cover improved consultation between the immigration service and police and updated guidance for chief constables.
Claude Moraes, of the Joint Council for the Welfare of Immigrants, described the review as 'tinkering'. He said: 'Body belts and handcuffs, private security firms and the fact that 9,000 people are detained each year will still be a firm and inhumane feature of the immigration enforcement system.'