The former Newcastle attacker, who also played for Rangers, made the comments during the Sky Sports’ Morning View show on Thursday morning.
“It is very frustrating, you would say,” said the 35-year-old. “They were looking safe and looking good, and suddenly now, the way they are playing, I cannot see where they are going to get the next win from…
“I don’t think that the depth of the squad has been good since the start of the season. I don’t think that Mike Ashley has brought in the players he probably should have…
“They got a lot of money for (Yohan) Cabaye. They should have used that money. Instead, they went for cheaper options and getting players for less money in to build them up and sell them on again.”
Investing in top players has been a problem for Newcastle in recent years, with the general perception being that club owner Mike Ashley is just happy for the Magpies to remain in the Premier League.
In the summer of 2014, the Premier League outfit did make some notable signings, but they have not quite worked out yet.
Siem de Jong has been injured for most of the season, Remy Cabella has been playing well only on occasions and has been rather inconsistent, while Emmanuel Riviere has been largely disappointing.
All three players came with a strong reputation, but neither was - or is - a world-class talent.
But perhaps it is not just the problem of signing top-class players. The players who were already in the team, such as Fabricio Coloccini, have struggled to be at their best.
Maybe an overhaul of the Newcastle squad in the summer of 2015 could be done to take the club forward and higher, but there is no guarantee that spending loads of money is going to make the Magpies a top-10 team.