The details will be sent to Old Trafford via Smith's agent Alex Black, who believes the transfer has now moved closer to completion.
"We have always made it clear that Alan will join as big a club as possible," he said last night. "He will sign only for a club that will offer Champions League football and Manchester United are the only club who fit that criteria who have made a firm bid so far."
The Leeds board will spend the weekend finalising personal terms with Kevin Blackwell, who has now been informed of their decision to appoint him as manager.
They initially planned to make an official announcement today, but the time needed to draw up Blackwell's contract means a statement is not due until Monday.
Prospective Elland Road buyer Steve Parkin is also believed to be happy with the appointment.