(Reuters) - The second largest U.S. mobile operator AT&T Inc reached agreements "in concept" with the Communications Workers of America in AT&T Midwest and AT&T Corp core wireline contract negotiations.

The Midwest contract covers more than 13,000 employees in Illinois, Indiana, Ohio, Michigan, and Wisconsin, while the AT&T Corp contract covers about 5,700 employees located throughout the country, the company said on Friday.

The company and the CWA will work through the weekend to finalize terms that could be presented to the labor union members for ratification, AT&T said.

AT&T had agreed last week to a one-year extension for a labor contract with the International Brotherhood of Electrical Workers, which covers nearly 7,000 workers.

The company has been engaged in tough labor negotiations this year as it looks to reduce costs to help offset the decline of its traditional home phone business.

AT&T did not provide further details in its statement.

(Reporting by Neha Alawadhi in Bangalore; editing by Carol Bishopric)