Feb 6 (Reuters) - Atmos Energy on Tuesday reported a rise in first-quarter profit, as lower costs helped the natural gas distributor offset the impact of lower demand for the heating fuel due to milder weather conditions.

The Dallas-based firm said its operation and maintenance expenses fell to $166.3 million from $185 million a year earlier.

Atmos delivers natural gas to more than 3 million distribution customers in over 1,400 communities across nine states located primarily in the south of the United States.

The firm said its consolidated net income rose to $311.3 million, or $2.08 per share, in the three months ended Dec. 31, from $271.9 million, or $1.91 per share, a year earlier.

Peers CMS Energy and Xcel Energy have also posted a rise in quarterly income, as the utilities also benefited from lower costs.

Atmos reaffirmed its full-year earnings forecast of $6.45 to $6.65 per share, compared with average analysts' estimates of $6.58 per share, according to data from LSEG.

(Reporting by Vallari Srivastava in Bengaluru; Editing by Shinjini Ganguli)