UPDATE 3-Canada's Niko raises "going concern" doubt, shares plunge
* Says may not be able to meet current liabilities
* Second-quarter loss widens, sales volume falls
* Hires United Airlines former CFO to advise on refinancing
* Plans to shed non-core assets in India, Trinidad
* Shares fall to life-low (Adds details from conference call, background)
By Garima Goel
Nov 15 (Reuters) - Canadian oil and gas producer Niko Resources Ltd lost more than half its market value after it raised "significant" doubt about its ability to continue as a going concern.
Niko said it was negotiating for a $340 million loan to avoid defaulting on debt payments and other obligations.
The company said it had a working capital deficiency of $110 million as of Sept. 30, while its cash and cash equivalents had dropped to $55 million from $98.1 million a year earlier. Continued...