FONTANA, Calif. (AP) _ Kaiser Steel Corp., operating under Chapter 11 bankruptcy protections from creditors since February, said Thursday it had agreed to sell its New Mexico coal operations to to a unit of Chevron Corp. for an undisclosed price.

The deal would nearly double the 1 billion tons of coal reserves of Chevron's Pittsburg & Midway Coal Co. of Englewood, Colo.

Kaiser still is seeking buyers for its other coal properties in Utah and Colorado.

In all three states, Kaiser has more than 1.3 billion tons of low-sulfur bituminous coal. The New Mexico property, at about 630,000 acres, accounts for the majority of that and is one of the largest such coal sources in the West not owned by the government.

The New Mexico holdings are located in Colfax County and consist of the York Canyon mining complex and adjacent properties.

Acquisition of the New Mexico holdings would ''approach doubling of P&M's current coal reserves,'' said P&M spokesman Fred Meuer.

P&M's biggest operations currently are in New Mexico at the McKinley Mine northwest of Gallup. It also has sizable operations in Wyoming and Alabama and smaller operations in Colorado, Kentucky, Kansas, Missouri and Texas.

Late last month, Kaiser said it had agreed to sell a Northern California pipe mill, steel fabrication plant and other properties for $13 million.

It is still seeking a buyer for its fabricated steel plants in Vallejo and Fontana, Calif.