The Sun says Kanu, 35, is planning to sue the 2008 FA Cup winners for SIX YEARS of unpaid earnings in a 'breach of contract' dispute.
The Nigerian claims the League One outfit owe him MILLIONS.
Pompey's administrators are keen to get Kanu's £300,000-a-year deal off the wage bill, And they believed they had found a way through breach of contract when the striker failed to report for pre-season on Monday.
But Kanu's agent Samuel Okoronkwo said: "We are claiming Kanu is owed millions.
"It is they who have breached the contract by not fulfilling contractual obligations. Until now he was prepared to wait.
"We will be pressing our claim through the Football League."