July 31 (Reuters) - PG&E Corp PCG.N on Thursday narrowly missed Wall Street estimates for second-quarter profit, as the utility firm was hit by an increase in operating and maintenance costs, sending its shares down 1.4% in premarket trading.

The company said its total operating and maintenance costs rose 3.7% to $2.86 billion, adding that wildfire-related claims, net of recoveries and the utility's wildfire fund expense increased from a year earlier.

PG&E has been blamed for sparking numerous wildfires, including some of California's most deadly, and has been making investments to improve the reliability of its power grid.

In a wildfire mitigation plan filed in March for the 2026-2028 period, the utility said it aims to build nearly 700 miles of underground power lines and complete 500 miles of additional wildfire safety system upgrades between 2025 and 2026.

PG&E's total quarterly operating revenue fell to $5.90 billion, from $5.99 billion a year earlier.

PG&E is the parent company of Pacific Gas and Electric Company, an energy company that serves 16 million Californians across a 70,000-square-mile service area in Northern and Central California.

The company said it added nearly 3,300 new customers in the second quarter to its electric grid system.

On an adjusted basis, PG&E reported a quarterly profit of 31 cents per share for the three-month period ended June 30, missing Wall Street expectations by 1 cent per share, according to LSEG.

(Reporting by Sumit Saha in Bengaluru; Editing by Shailesh Kuber)

((Sumit.Saha@thomsonreuters.com;))