Mystery surrounds Helder Costa’s future after he was included on the Premier League’s official list of retained Wolves players despite agreeing a seemingly cast-iron £15million move to Leeds United.

The Portugese winger moved to Elland Road last July when it was announced he had signed on an initial season-long loan that would become a permanent transfer this summer.

There has been so suggestion that the deal could fall through or was based on certain criteria being met.

But the Premier League’s official retained list released in the last 24 hours names Costa among the senior professionals staying on at Wolves.

Leeds announced earlier this month that Costa would complete the season at Leeds as part of his original loan.

Bafflingly, the retained list does not state that he is merely staying on the books of the Premier League high flyers for the rest of this season.

That is the case with three others Wolves players – John Ruddy, Cameron John and James Pardington.

There could, of course, be an innocent explanation, such as an administrative error by Wolves or the Premier League.

Nevertheless, the Premier League document is baffling given that Costa has signed a four-year contract with Leeds that had been set to come into effect on 1 July.

The Championship leaders have already paid an initial multi-million loan fee to Wolves to take Costa for this season.

They are then set to pay the transfer fee in multiple payments running up until 2024.

Costa has been a mainstay of the Leeds team fighting for promotion this season.

The Portugal international has made 28 Championship starts among 41 appearances in all competitions, scoring four goals and supplying five assists.

In other Leeds United news, it can be REVEALED the Whites have set their sights on raiding a Premier League side this summer.

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