Coal explorer Northern Energy Corporation Ltd (ASX: NEC) is thwarting the $193 million unsolicited takeover bid by New Hope Corporation (ASX: NHC), calling the proposal as inadequate and materially undervaluing the firm.

In a released statement, Northern Energy said on Thursday that New Hope's $1.50 per share offer was deliberately made at a time of weak share prices due to the imminent new mining tax set to be imposed by the federal government and mine approval delay issues.

The company said that the timing and circumstances surrounding the offer was simply opportunistic, which it maintained "does not reflect the inherent value in the Northern Energy portfolio of assets, nor does it reflect the strategic value of Northern Energy's project pipeline."

Northern Energy chairman Dr Chris Rawlings also said that the company board deemed the takeover proposal as largely inadequate as he stressed that the acquisition bid was put forward at a time when the company is right on track to commence coking coal production on its Maryborough mining site come 2012.

Apart from that, Dr Rawlings said that testing and assessment procedures were now underway at Maryborough for possible expansion moves as he gave assurance that updates on these initiatives would be furnished to the market in due time.

As the news of the acquisition offer filtered through the market on Wednesday, Northern Energy saw its shares closing at $1.575 while New Hope closed down trading at $5.29.