There's been no advance by Seamus FitzPatrick's Capvest vehicle on a preliminary approach made last month for investment group One51, which placed a €288m valuation on the business.
Releasing interim results yesterday, One51 confirmed that since the initial approach was made, "there have been no further developments with respect to this possible offer".
"The company continues with its strategy to develop its core operating businesses while continuing to assess appropriate liquidity options for shareholders," it added.
One51, which owns almost 24pc of NTR, paid just over €200m in July to acquire a 67pc stake in Canadian plastics firm IPL.
One51 also owns recycling and waste disposal businesses.
Its earnings before interest, tax, depreciation and amortisation (EBITDA) rose 22.9pc to €13.3m in the first six months of 2015, while revenue was 10.2pc higher at €141.9m.
Chief executive Alan Walsh said the results represented a "solid" performance during the period.
Mr Walsh said One51 had more than halved its interest bill in the past six months after renegotiating banking arrangements and cutting debt.
One51 said that the growth in the first half of the year was driven by its plastics division.
It's expected that One51 investors will hold out for a higher offer than the €1.80 a share valuation placed on the business by CapVest.
Co-ops including Kerry Co-op and Dairygold are investors in the firm.
So too is beef baron Larry Goodman and Pageant Holdings, the investment vehicle controlled by Nick Furlong. Pageant owns an 8.3pc stake in One51. Financier Dermot Desmond is also an investor in One51.