Twenty-five years after the first national campaign against Aids warned "Don't die of ignorance," a Lords committee has called for a new drive to curb the spread of the disease.

The number of people infected with HIV is expected to top 100,000 by next year and the numbers in treatment have trebled since 2000 at a cost of almost £1bn a year. Yet efforts to prevent the disease are "woefully inadequate", the report says. More than a quarter of those infected have not been tested and are unaware of their condition, increasing the risk that they will pass on the infection.

Just £2.9m was spent on HIV prevention in the last year compared with £762m on treatment. Avoiding one infection saves treatment costs estimated at £280,000-£360,000.

The report, by the House of Lords HIV and Aids Select Committee, was chaired by Lord Norman Fowler who, as health secretary in 1986, launched the "Don't die of ignorance" campaign.

Lord Fowler said: "In the last 25 years the development of new drugs has dramatically reduced the death toll but that should not encourage a false sense of security. Prevention must be the key policy."