An influential all-party Commons committee rounded on Mr Howard saying that prisoners and the public were being fooled into thinking the man who investigates injustice in the country's 136 jails has greater effectiveness than he has.
"From what we have heard he is not an ombudsman.
"He is a complaints investigator who does as much as the Home Office allows him to do," said Michael Lord, Conservative MP for Suffolk Central.
MPs were attacking Mr Howard's decision on Tuesday to impose three restraints on Vice Admiral Sir Peter Woodhead's powers to investigate inmates' grievances: they restrict his access to documents making him dependent on what the Prison Service chooses to hand over; it removes his right to investigate or even check any decisions by ministers or advice to ministers; and it requires him to provide draft reports for Prison Service checking before publication.
Sir Peter, who took up his post in April 1994, had told the Select Committee on the Parliamentary Commissioner for Administration that he was greatly concerned and disappointed by the changes, which further eroded his already "flaky" independence.
"The terms of reference, in my opinion, give too much control to the very organisation which is under scrutiny," Sir Peter told the committee.
"I think it is very important that I am seen to have that level of independence that gives me credibility with all parties. It affects not only my status but the status of other ombudsmen," he said.
He said the cases affected by the changes would be small - up to 6 per cent of its 1,800 a year - but the most important ones, often relating to the more vulnerable inmates.
He said the erosion of his rights to examine documentation would legitimise what he suspected had already happened in some cases - that files had been "weeded" before submission to him, although he had no proof. He also complained of delay in getting access to papers. In about 10 per cent of cases, Prison Service papers take a month or more to reach him, making the system too bureaucratic for short-term prisoners, remand inmates and young offenders, he said.
But Richard Wilson, permanent secretary at the Home Office, denied that there had been any "hanky panky" or "obstruction" with the work of the prisons ombudsman. "If it came to my attention that that was the case I would take an extremely serious view of it and expect the ombudsman to bring it to my attention."
He said Mr Howard changes were mere clarification of what had always been government intention ever since an ombudsman for prisoners was first recommended by Lord Woolf in his inquiry into the 1989 Strangeways riots.
After the hearing Sir Peter said that despite losing his powers he had no intention of resigning "at this stage".
"It is important for both my staff and the work they are doing and particularly for the prisoners that we do the best we can for them."