Barcelona star and Dutch international captain De Boer tested positive for the banned steroid nandrolone after a Uefa Cup quarter-final against Celta Vigo on 15 March.

He was suspended for 12 months on 14 June before a Uefa appeals body cut his ban after finding that contaminated food supplements were "more than likely" for the positive test.

De Boer is now allowed to start playing from 1 September but has instructed his lawyers to start legal action.

"I am innocent and I have spent a lot of money trying to demonstrate it," De Boer told the Spanish press.

"That is why I am demanding that justice is fully done, and this is the only way to achieve it."

Cor Hellingmann, the 31-year-old player's lawyer, said: "The Uefa judgement was not fair.

"The player was not declared guilty and yet there was still a punishment that prevented him from exercising his legitimate right to work and that is why we are bringing the case."

Holland play the Republic of Ireland on 1 September but De Boer has an Achilles injury and is unlikely to figure.