Chrysler's creditors plan to make a counteroffer to the U.S. Treasury this week, in which they might ask for equity in a firm combining Chrysler with potential partner Fiat SpA in exchange for concessions, the Wall Street Journal reported, citing people familiar with the matter.

Sources told Reuters on April 3 the lenders for the $7 billion loan, which include JPMorgan Chase & Co , Citigroup Inc , Goldman Sachs Group Inc and Morgan Stanley , were in talks with the government to reduce Chrysler's debt by swapping some of it out for equity, new debt or a lesser amount in cash.

The government had suggested a reduction of as much as $6 billion in Chrysler's debt, a separate source close to the talks told Reuters at the time.

Late Sunday night, the lenders received 20 to 30 pages of data and financial models from the Treasury, the Journal reported on Monday.

These documents show government assumptions on Chrysler's cost structure, its internal operating results, information on new union contracts and details on Fiat's contributions to a joint company, the paper reported on its website.

Officials from Chrysler, Stairway, Oppenheimer and Perella Weinberg were unavailable for providing comment to Reuters.

Italy's Fiat and Chrysler are trying to finalize a partnership by the end of April that would help the U.S. carmaker avoid bankruptcy.

The lenders' steering committee, which has been largely controlled by the big banks, was expanded this weekend to include three other debt holders -- Oppenheimer & Co, distressed investor Stairway Capital Management and investment bank Perella Weinberg Partners, all of which hold pieces of Chrysler bank debt, the Journal reported, citing sources.

The decision to expand the committee's ranks was made late Friday, after several of the nonbank creditors had taken steps to set up an alternative committee of creditors, the Journal reported.

(Reporting by Anupreeta Das; Editing by Anshuman Daga)