Nevertheless, his department said later that officials were continuing to seek a definition, and Mr Howard said that if the Opposition could come up with a working solution, he would not hesitate to implement it.
During heated Commons exchanges in a Queen's Speech debate on home affairs, Mr Howard accused Labour of trying to whip up an "entirely synthetic fuss about knives" to divert attention from government proposals to deal with serious, violent offenders.
But he also made an offer that had not been made when the Prime Minister wrote to the Labour leader, Tony Blair, last Thursday - that if the shadow Home Secretary, Jack Straw, or others, did come up with a proposal, "we would be entirely happy to sit down with them and discuss it".
It is now likely that Labour will make a firm proposal on a form of legislative wording, leading to all-party discussions along the lines offered by Mr Howard.
Mr Howard told the House that the problem was that neither he nor the police had been able to find a definition that would not at the same time ban lawful household and other knives.
But Mr Straw intervened to point out that a spokesman for the Police Superintendents' Association had said on ITN's lunchtime news that if a man could be sent to the Moon, then it must be possible to find a definition of a combat knife. Holding up a copy of a gun magazine, he read out an advertisement for "the Vindicator - a special-operations knife, quarter- inch stock, 12 inches overall: pounds 145". Mr Straw added: "This has no purpose whatsoever but maiming and killing people."
Clearly angered by the Labour attack, Mr Howard then produced a letter from the Association of Chief Police Officers, written last May, in which they said: "We agree with you on the impossibility of defining an undesirable dangerous knife without also catching other knives, which should not be banned.
"We can all sympathise with the public view that certain types of hunting knife should not be on sale, but their definition would be difficult and the benefit dubious if carving and other catering knives are to remain available." Mr Howard also said that the superintendents' association had issued a press release yesterday, in which they said their views "mirrored" his own view.
He told the House that having been invited to offer a definition, all Labour had done was to launch a petition calling for a ban on combat knives.
"What we need are definitions, not petitions," Mr Howard said, "and rather less of the trivialising gesture politics".
He added later: "As soon as we have a definition, if such can be produced, of a combat knife, we shall not hesitate to use the procedure which we've used in the past. I've no hang-up about using that procedure and I would be delighted to use it. The only difficulty is the purely practical one of finding a workable definition."Reuse content