Ralf Schumacher thinks he knows why Lewis Hamilton's contract negotiations are taking so long.

Mercedes boss Toto Wolff said earlier this week that he hoped to get the seven time world champion's signature on a new deal by Sunday's Canadian GP.

But Hamilton, 38, then said in Montreal that it could actually take another month - amid rumours he is demanding a full five-year deal and more money per season than is earned by current champion Max Verstappen.

Former F1 driver Schumacher, however, thinks the real reason for the delay is because Mercedes and Daimler CEO Ola Kallenius has been drawn into the talks.

"Lewis will not drive forever," he told Sport1, "but he wants to stay connected to his motorsport home Mercedes after his career as well.

"However, Toto Wolff cannot negotiate such a long-term contract. That is Kallenius' area of responsibility. That's why it can still take a while yet," added Schumacher, whose nephew Mick is the reserve driver at Mercedes.

Hamilton appeared to confirm that as he said in Canada: "It's more complicated than usual because it's not just a simple driver contract." body check tags ::