"The consortium has produced the first of a number of documents showing that we have the funds in place to complete the transaction," he said.
But Leeds have insisted they were still some way from concluding any takeover.
However, Sainsbury believes he will have control of the club by the middle of next week.
"We appreciate the efforts that the board has gone to in extending the time in which to make available to them our proof of funding," Sainsbury said in a statement.
Waiting by, with great interest, is Yorkshire property tycoon Norman Stubbs, a Leeds supporter who has held his own negotiations with the board regarding his own takeover.