A handful of top-level Dutch sports men and women have admitted using doping in a confidential survey carried out by the Dutch doping authority.

In total, 291 of the 740 sports men and women who have the official status of ‘top sporter’ took part in the survey, news website nu.nl says.

Of them, 3.7% said they had manipulated their blood to improve performance and 0.5% had used other performance enhancing methods. Nu.nl did not give further details.

Blood doping is the practice of boosting the number of red blood cells in the bloodstream in order to enhance athletic performance. In particular, the use of EPO has been popular among endurance cyclists.

Half of the athletes who took part in the survey are subject to regular controls and have to report their whereabouts to sporting body officials. They are checked an average of 2.5% times a year and 11% are required to give blood samples.

The figures were published at a conference on doping on Thursday.

Sports minister Edith Schippers told the conference she had allocated €300,000 to draw up an anti-doping action plan.