Special cells for disruptive young offenders were used in 13 different juvenile establishments last year, despite earlier Home Office assurances that they were only used at Stoke Heath Young Offenders' Institution.

The Howard League for Penal Reform raised concerns about the cells in Stoke Heath, which have no toilet or furniture, after it emerged one young man had been held there for five days (news, page 6, 4 December).

Phil Wheatley, the Prison Service's director general, said the case was "extraordinary" (letters, 18 December) and, last month, a Home Office spokesperson told Community Care: "We are as certain as we can be that the special cells you refer to are not being used by juveniles in other prisons."

Yet, in response to a parliamentary question last week, prisons minister Paul Goggins revealed that special cells were used on 154 separate occasions by 13 different juvenile establishments last year. Six more establishments had cells but did not use them.

Howard League director Frances Crook said: "I don't know whether it's a cover-up or incompetence. Either way it is pretty worrying."

Huntercombe YOI in Nuffield used the cells the most frequently, on 46 occasions, followed by Feltham YOI, west London, which used them 32 times.

Special cells in Bullwood Hall Young Offenders' Institution, which holds female young offenders, were used three times last year.

Goggins failed to confirm how long children had been held in the cells, but said they were only used for "the temporary confinement of a violent or refractory prisoner, not as punishment".

A Home Office spokesperson insisted this week that, as soon as the original justification for using the cell had ceased, a young person would be removed. Confinement would usually be for "a small number of hours" and only in "very exceptional cases would it be longer".

But Crook said children had alleged they had been held in special cells for "several days". She slammed the practice as "child abuse" and called for the cells' abolition.

Mark Oaten, Liberal Democrat home affairs spokesperson, who tabled the question, said the Home Office should explain what happened in the cells and exactly how long children were held for. "Until that happens, we simply cannot accept the government's assurances," Oaten said.