Aberdeen manager Derek McInnes rued the loss of Adam Rooney to England's fifth tier after the forward completed a move to Salford City.

Rooney has brought his four-and-a-half year stint with the Dons to a close by penning a three-year deal with the ambitious National League newcomers.

The Irish attacker was the Dons' top marksman across each of his full seasons at Pittodrie.

McInnes said he offered neither Rooney or Salford any encouragement to make the move but eventually gave the switch the green light after a chat with the 30-year-old striker.

He said: "It's with a heavy heart that he moves on, he's a fantastic boy.

"Adam gave me his reasons as to why he wants to move on, he was given no encouragement and Salford were given no encouragement to do a deal.

"We spoke to him and said the opportunity to remain and fight for his place was there but these things happen, we wish him well.

"It's a surprise, maybe, where he has ended up but we'll now try and use the money we got for Adam to bring in someone else.

"What is clear is Salford are a very ambitious club, they are in a hurry to get through the leagues.

Rooney becomes the latest player to switch from Pittodrie to England's lower leagues, with Fraser Fyvie and Ryan Fraser amongst those to go south in recent years.

McInnes said the Reds face a continual challenge to warn off potential English suitors from poaching their top talent.

He added: "Like I say, Salford were given no encouragement but they've certainly shown ambition to get Adam.

"It is a challenge for us to retain our players a lot of time, we've lost players to League One which I don't think a club like Aberdeen should be.

"I see the levels but there is no criticism about it, Adam has gave me his reasons why he wanted to go and Salford are in a hurry to do well.

"It's disappointing but we deal with it and will try to get players in."

With a Europa League showdown with Premier League outfit Burnley looming, McInnes said Rooney's departure reinforces the need for the Dons to quickly bolster their front-line.

"There are a couple of key areas," he said. "I was looking to bring in a forward anyway but that becomes even more pressing.

"The timing isn't ideal, we've known about this for the last few weeks and tried to delay it as long as we could but it came to the point where we ran the risk of losing the deal for Adam and I'd gave him my word.

"We're concentrating on bringing in a front player and a right-sided defender, they are the key positions.

"I think there's this feeling we are able to go out and pay x amount on player wages and transfer fees, we don't it's difficult.

"It's becoming more of a challenge to improve and get players here to the club but it is one we are prepared to meet head on.

"The Burnley game highlights the importance of getting players in quickly."