Dutch national team captain Frank de Boer faces the prospect of a lengthy ban after his club Barcelona confirmed his B-sample had proved positive for the banned anabolic steroid nandrolone.

"We can confirm that Barcelona have been informed that the player's B-sample is positive," a spokesman for the Spanish club said yesterday. The 30-year-old defender continued to protest his innocence, although he admitted he would find it difficult to clear his name given the experience of his Dutch colleague Edgar Davids, who tested positive for nandrolone earlier in March.

"It is going to be very hard to show that I have taken nothing," said De Boer, who has been called up together with Davids to play in his country's World Cup qualifier against Estonia at the weekend.

"Davids and the Dutch Federation have investigated the food supplements we took when we were with the national squad and they have been found to be nandrolone-free. I know I am innocent and everything I have taken has been totally legal."

The UEFA disciplinary committee, which is due to meet on June 14th, is likely to make a decision on the De Boer case. "Until then the player will continue playing for the club and we will consider what action we will take when we know the sanction that UEFA decides upon," the spokesman added.

De Boer's A-sample produced a result of 8.6 milligrams per litre of blood, over four times the permitted level. A ban of between six months and two years is the normal punishment issued when players have tested positive for banned substances like nandrolone.