Newcastle officials are trying to place a player with Leeds to avoid paying a transfer fee for hooker Danny Buderus, who has agreed to return home next season if the two clubs can come to an arrangement over the remaining year of his contract with the Rhinos.
It is not believed that Kaufusi, McDonnell, Mika or Karawana have been asked to take part in a player trade with Leeds, who are asking for up to $150,000 compensation to allow Buderus to return home to the Knights. The Rhinos want a replacement player of similar stature to Buderus, but not necessarily a hooker.
Riolo is believed to have also explored Super League options for Kaufusi and the former Storm and Cowboys front-rower has confirmed he is considering offers to leave the Knights, despite being under contract for next season.
Reports from England last night said the Harlequins were set to announce the signing of Kaufusi.
McDonnell, who is off contract, and Karawana have also been linked to Super League, while Mika is considering a switch to rugby union.