All three clubs had scouts present in Turkey on Friday when Iceland stunned their woeful hosts 3-0 in a World Cup qualifier, with Palace certainly there for Tosun - who led the Turkish forward line.
Representatives of Spurs and the Magpies also saw the Besiktas striker in action last week in a 2-0 Champions League win over RB Leipzig.
Reports in Turkey claim the same two Premier League clubs who were said to be watching Tosun when he netted a long-range strike away at Porto on matchday one, were in attendance at Vodafone Arena.
Atletico Madrid and Sevilla also sent scouts to the Champions League match to watch the 26-year-old German-born forward, who set up his side's opening goal for Ryan Babel.
Tosun scored 20 league goals for the Turkish title-winners last season so it is no surprise to hear that foreign clubs are watching him, but Spurs could also have been watching three players in the Leipzig side.
Mauricio Pochettino's men have been linked to Germany striker Timo Werner, Portuguese winger Bruma and French forward Jean-Kevin Augustin in the last 18 months.