May 8 (Reuters) - U.S. rare earths producer MP Materials ( MP )

said on Thursday that it swung to a first-quarter loss

due in part to rising production costs and interest expenses,

though results met investors' expectations.

The results are the first since the Las Vegas-based company

said last month it would stop shipping the critical minerals to

China for processing in response to Beijing's tariffs.

The move essentially halts a major source of revenue for the

company, although its impact will not reflect until

second-quarter results, expected in August.

For the first quarter ended March 31, the company posted a

net loss of $22.6 million, or 14 cents per share, compared to

net income of $16.5 million in the year-ago period.

Excluding one-time items, the company lost 12 cents per

share, matching analysts' expectations, according to IBES data

from LSEG.

Shares of the Las Vegas-based company fell 1.3% in

after-hours trading.

MP said its cost of sales, excluding depreciation and

related items, increased by roughly $13.3 million, due in part

higher production costs associated with the low utilization of

its refining facilities. The company is increasing the use of

those facilities.

MP's interest costs also rose by nearly $5 million due in

part to rising expenses tied to a convertible note due in 2030.

MP produces rare earths concentrate at its California mine

that it had sold to refiners in China, until last month, and

elsewhere. It also refines rare earths in California.

The company produced 12,213 metric tons of that concentrate

during the quarter, 10% higher than the year-ago period.

At its California refinery, MP produced 563 metric tons of

neodymium and praseodymium (NdPr) - the two most in-demand rare

earths - during the quarter, more than four times the year-ago

period.

Realized prices of rare earth concentrates during the

quarter rose 12% from the year-ago period, though prices for

NdPr fell 16%.