The Science and Technology Committee has published a report ahead of Nerc's council meeting tomorrow, at which the final decision on the merger will be taken, following a public consultation.
The decision was originally due in December, but widespread concern over the proposal and Nerc's concerns about the possible effects on staff morale prompted it to bring the decision forward. It is expected to be publicly announced early next week.
Nerc has argued that the merger would save money and facilitate greater scientific synergy and impact in an era in which climate change was causing polar and ocean science to merge.
But critics lamented the loss of the iconic British Antarctic Survey name and worried it could herald a downgrading of the UK's commitment to maintaining a presence in the South Atlantic.
The committee's report says it has received complaints that Nerc "has not provided an adequate evidence base to support its case for a merger, with the absence of projected cost savings being particularly notable".
"In addition, Nerc does not appear to have given adequate consideration to the British Antarctic Survey's geopolitical role," it adds.
Committee chair Andrew Miller said: "Given the world-renowned and respected brand of the British Antarctic Survey it should require the strongest possible case to be made to merge it into a science institution that does not have the same iconic status."
In a hearing earlier today, Nerc chief executive Duncan Wingham told the committee that the main driver for the merger was increased scientific synergy, but added that it would save the organisation around £500,000 a year.
"That may not seem much, but we have been seeking those kinds of savings in many places...We can't not respond to the circumstances we are in [but] it is hardly something we welcome."
Nerc's flat cash budget is expected to have declined by 11 per cent in real terms by the end of the current spending period.
David Willetts, minister for universities and science, told the committee he was mindful of the Haldane principle and was reluctant to interfere in the way Nerc organised its science. He said he trusted Nerc's council to take the final decision.
But he said the research council was aware of its "dual mandate" to implement the government's commitment to maintaining the UK's "level of activity" in Antarctica, and said he had been assured that it was not under threat.
He said he was considering introducing a "discrete funding line" for Antarctic science within the science budget to prevent future anxieties.