Oil and gas company Apache Corp has rejected a takeover approach from an unidentified party, reported Reuters.

The potential buyer had sent a letter to Apache in the “past few weeks,” but it was not clear if the talks would resume

The company had reported a much smaller-than-expected quarterly loss on Thursday, although it raised its full-year production forecast.

According to Bloomberg the Houston-based company is working with financial adviser Goldman Sachs Group Inc. on defense against the takeover bid.

The company is worth more than $18b so a deal for Apache would be the largest for an independent oil and gas producer in the US this year.

Apache, a major shale producer in the US and globally, has been selling off failing properties in Texas and Australia to keep afloat.