By Gina Keating

LOS ANGELES (Reuters) - The Illinois attorney general subpoenaed units of Countrywide Financial Corp CFC.N and Wells Fargo & Co (WFC.N: Quote, Profile, Research) on Thursday in an investigation of whether the companies violated federal lending and civil rights laws by steering minority borrowers into more expensive loans.

The action by Attorney General Lisa Madigan follows a Chicago Reporter magazine study that found Chicago led the United States in high-cost home loans and revealed disparities in loan pricing between white and non-white borrowers.

Madigan said in a statement that her office was looking into reasons for the pricing disparities and whether the differences were based on valid underwriting and credit-worthiness.

Countrywide's lending practices are already being investigated by federal and state authorities and it is being sued by investors and mortgage holders.

Countrywide, the largest U.S. mortgage lender, said on Thursday it would cooperate in any investigation by the Attorney General.

"The company continually analyzes its data and take steps to ensure that the borrowers are treated fairly," Countrywide said in a statement.

"Countrywide is proud of its record of expanding the opportunities for home ownership among low-income and minority communities and welcomes the opportunity to review its practices with the Attorney General," the company said.

Wells Fargo denied that race was a factor in its lending and said that credit and risk factors explained all of the differences in pricing.