The Medical Research Council has cancelled a £10m research study examining the benefits and risks of the long-term use of hormone replacement therapy (HRT).

The council said it was being stopped for "scientific and practical" reasons, and stressed there were no safety concerns for the 5,700 women involved.

Earlier this year, a similar trial in the US found that taking HRT long-term did not have a major effect on preventing heart disease. This was one of the main scientific questions the UK study, known as Wisdom (Women's International Study of Long Duration Oestrogen after Menopause), was seeking to answer. The study also wanted to assess the effects of HRT on conditions such as breast cancer, osteoporotic fractures and dementia.

When the US results emerged, the MRC set up an independent international committee to review other findings made abroad that could affect of Wisdom's study.

The committee concluded that the Wisdom study was taking too much time, and with results not expected until 2016, the results would now be "unlikely to influence clinical practice."

An MRC spokesman said it was not yet clear how much money had been spent on the trial, which began in 1999. "Studies of this kind happen all over the world. It's impossible to know everything that is happening," he said.

Ray Fitzpatrick, professor of public health and primary care and director of the institute of health sciences at the University of Oxford, who chaired the committee, said: "When the Wisdom trial began recruiting in 1999, there were important questions about the risks and benefits of taking HRT long-term that needed to be answered. But since then new findings have provided evidence in relation to those questions."

The US trial found taking HRT increased the risk of breast cancer but decreased the risk of osteoporosis. No evidence was found to suggest it affected the development of cardiovascular disease.

Professor Janet Darbyshire, director of the MRC clinical trials unit, which coordinated the study, said: "As researchers we are naturally very disappointed when a study is stopped early. However, it's the nature of science that new evidence emerges all the time which has an effect on existing studies."

All those involved in the study, including the women, have been sent letters from the MRC advising them of the cancellation.