The 29-year-old has also picked up a knee injury which will almost certainly rule him out of the English club’s final match of the season on Saturday.

He hobbled off in the early stages of last week’s 1-0 defeat by Nottingham Forest and that looks to be that after five years at Victoria Park.

The Hartlepool Mail has speculated that Porter will now turn his back on United and agree a three-year deal with the Wellington Phoenix – the New Zealand club having publicly confirmed its desire to land the player.

Hartlepool boss Danny Wilson said: “Something in Joel's knee has gone wrong and we will assess it but it is quite sore. To lose another striker was a blow for us.

“I don’t know how bad Joel’s injury is but it wouldn't surprise me if that was his season over with the luck we have been having. I hope it is not but you never know.

“Until we get the last game out the way and then the chairman decides whether we keep players or not, we won’t know if that's the last we see of Joel.

“We put our recommendations in and see what happens.

“That’s the prerogative of the club. It’s a bit frustrating for the players I suppose but that’s the way it is.”

The Phoenix have made Porter’s representatives aware of their interest and expect a decision once the English season has reached its conclusion.

Porter’s capture would provide extra firepower to assist last season’s leading scorer Shane Smeltz and former Newcastle Jets front man Troy Hearfield.