The Magpies are expected to lose Spanish defender Enrique, reportedly to fellow Premier League side Liverpool, before the end of the transfer window, and Krul has revealed that Pieters is Alan Pardew's top target after failing to seal a deal for Swansea's Neil Taylor.
"We are interested," Krul told De Telegraaf of his Dutch international colleague Pieters.
"The coach himself and the assistants have already seen a few matches of PSV and the question now is whether the clubs can work it out.
"Our current left-back Enrique has a contract that expires, however, he won't sign and is interesting many clubs."
And the 23-year-old keeper admits he would love for Pieters to join him on Tyneside, adding: "Erik is my friend since we played together at the World Championships in Peru in 2005."
Pieters, also 23, has been the first-choice left-back for the Netherlands since Giovanni van Bronckhorst retired in 2010, and currently has 10 caps for Bert van Marwijk's World Cup finalists.