MEXICO CITY, Nov 12 (Reuters) - Mexican retailer Comercial Mexicana has started the process to swap around $100 million worth of defaulted short-term debt for new commercial paper maturing in seven years, the company said on Thursday.

The move, announced in a filing with the Mexican stock exchange, is part of a recent restructuring deal with a group of creditors that included local pension funds and retirees.

The company, known as Comerci, defaulted more than a year ago after its derivatives bets soured due to a steep peso depreciation.

After long and difficult negotiations, Mexico's No. 3 supermarket operator offered to pay back $1.535 billion to all creditors, in a mix of cash from ongoing operations, notes guaranteed with assets and convertible bonds.

While the general terms of the debt restructuring have been agreed upon with most key creditors, a smaller group of bond holders are still negotiating with Comerci over their payment. (Reporting by Cyntia Barrera Diaz)