Routine breast cancer screening may have little effect on reducing deaths from the disease and the value of national programmes should be questioned, according to a new report.

A study by the Nordic Cochrane Centre in Copenhagen, published recently in the British Medical Journal, concludes that national screening programmes bring no benefit in terms of lives saved. The study, based on the Danish programme, is the latest work to raise questions about the efficacy of population-wide mammographies. It comes as the world's leading disease experts gather at the European Breast Cancer Conference in Barcelona.

All women aged between 50 and 70 are offered breast cancer screening in Britain, with more than 1.7 million taking up the invitation every year.

The latest findings, based on analysis of data over a 20-year period covering the introduction of regional screening in Denmark, found that breast cancer mortality fell by 1% per year in the screened areas and by 2% per year in non-screened areas.

The research authors, from the University of Copenhagen and the Norwegian Institute of Public Health, conclude that they could find no effect of the Danish programme on death rates.

They write: "Our results are similar to what has been observed in other countries with nationally organised programmes. We believe it is time to question whether screening has delivered the promised effect on breast cancer mortality."

The government, health charities and most doctors encourage women to have regular mammograms in the UK on the basis of estimates that the checks save 1400 lives each year.

However, last year a group of leading health professionals told The Times that women undergoing routine breast cancer screening were not being warned of the risks, with many tests ending in needless treatment. They criticised the government's "unethical" failure to provide women with the full facts in the NHS programme of checks.

Of the 2.2 million women invited for checks in 2007-08, 1.7 million were screened - up half a million on a decade ago. The number of cancer cases detected by screening has more than doubled over the same period to 14100.

However, a spokesperson for the NHS Screening Programmes said that the conclusions published in the BMJ added little to the ongoing analysis of breast screening.

Professor Julietta Patnick, the director of the NHS Cancer Screening Programmes, said: "Rigorous independent research has shown that the NHS screening programme saves lives. This is a report relating to the Danish screening programme which is significantly different from the English system."

A report from the World Health Organisation's International Agency for Research on Cancer suggested a 35% reduction in mortality from breast cancer among regularly screened women between 50 and 69 years old.