Newcastle United boss Eddie Howe has warned that the Magpies have no margin for error in the transfer window any more.

With the PSR rules wrapped tightly around club finances, Howe knows that expensive transfer failures could set United back years if they don't do their homework right. As Newcastle prepare a scouting summit this weekend - with Toon talent spotters set to be briefed by sporting director Paul Mitchell on what will be needed going forward - Howe also issued his own stance on recruitment.

After spending £223m on the spine of their team and getting it right in big deals for Anthony Gordon, Alexander Isak and eventually Sandro Tonali, Newcastle go into the summer window with money to spend but knowing they must do so wisely.

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Howe said today: "It's very slim because if you look a those signings (Guimaraes, Botman, Gordon, Isak, Tonali, etc) and we didn't get them right, we're left in a really awkward position because the impact of PSR is so big that the trade-off in terms of trying to maybe move players on that you're not happy with and then replacing them, that becomes very messy.

"Now, I know every team will say the same, that failure in the transfer market was always a very costly thing, but I think in this world, it's even more costly, so that's where the importance of future signings comes into play.

"Those historical signings, I think, have been absolutely outstanding for us and I've said before I wouldn't change any of them. They've been magnificent. But the importance of future recruitment takes on an even bigger focus in the future."

Tonali had to endure a 10-month global ban after getting caught up in an illegal betting scandal in Italy. But Howe feels that the £55m star is now settling in at St James' Park.

He said: "Unfortunately, we lost him, but for me, he's multi-talented and the profile we were looking for was someone that could play multiple roles in midfield, not just one.

"He's everything that I hoped he would be and more, really. I think he's really improving all the time The training he did in between the ban I hoped would pay dividends for him long term, but without that match stimulus, I think it was always difficult to see how much he had evolved and changed during that time.

"But I think now we're seeing that there's real growth in his performances."