Calfrac Well Services said on Tuesday it had rejected two proposals submitted by share and debt holder Wilks Brothers to buy the Canadian oilfield services firm's U.S. business in exchange for some of the company's debt.

Calfrac said the two non-binding proposals submitted last month "significantly undervalued" the unit and would leave its first-lien senior creditors with less than one-third of the collateral they currently hold, with no debt reduction.

Last month, the Canadian company said it would work with advisors to examine its options as its market value had collapsed and it deferred an interest payment on debt that does not mature for six years.

The company, which had a net debt of C$987.4 million ($725.34 million) as of March 31, said on Tuesday that it agreed with some debtholders to restructure some of its debt and issue some new shares.

Wilks Brothers LLC holds about 19.78% of Calfrac's shares and more than 50% of its second-lien notes, and also owns ProFrac Services Ltd, a competitor of Calfrac in the U.S.

(Reporting by Arunima Kumar in Bengaluru; Editing by Amy Caren Daniel)