Sports Direct has vowed to fight on for ownership of stakes in rival retailers after apparently losing control of them to the administrator of collapsed Icelandic bank Kaupthing.

Sports Direct this week lost its 29% and 11% holdings in Blacks and JD Sports Fashion respectively. Kaupthing helped finance Sports Direct’s share purchases and held guarantees over them. Ownership of the stakes was disputed after the Icelandic financial meltdown.

Kaupthing administrator Ernst & Young applied to a judge for a ruling that Sports Direct does not own the shares, allowing Blacks and JD Sports to notify the stock market that the shares had changed hands.

Sports Direct, which has written off the £53m value of the stakes, said it “continues to resist any effort by the administrator of Kaupthing Singer & Friedlander to appropriate Sports Direct’s strategic investments”.

It is taking action against Kaupthing and Ernst & Young to “protect and vindicate our legal rights”, it added.