The supermarket has written to suppliers to tell them it has changed its payment terms from 30 days to 60 days as of December 1st, 2008.
The Financial Times reported that it had seen a leaked letter from Tesco finance director Eamonn O'Hare that said the decision was the result of a "detailed review of our non-supplier [sic] terms, with the aim of improving consistency, transparency and efficiency across our non-food supply chain".
In a statement, Tesco said: "This is a move to align payment terms for our larger non-food suppliers across the Tesco group which currently vary from country to country and within product categories.
"We have written to suppliers to seek their agreement to the change and hope to implement it before the end of the year."
The move is part of a global review, the grocer added.
However, the FT speculated Tesco planned the move to free up millions of pounds in capital for the Christmas period.