University think tank Million+ raises concerns that some disadvantaged students could miss out if there are different funding options depending on the university they attend, or if funding is linked to academic criteria, such as A-level grades.
As part of plans to triple tuition fees, Ministers agreed to establish a new 150m National Scholarship Programme (NSP) to ensure poor students are not priced out of higher education.
Days before last month's tuition fee vote Deputy Prime Minister and Liberal Democrat leader Nick Clegg announced that bright young people from disadvantaged backgrounds could have up to two years of their university tuition fees paid for them.
The proposal, being considered by a steering group, is for poor students to have their first year paid for by their university, the NSP then funding their final year, rewarding those that stick to their course.
But the Million+ policy document says: "The steering and operational NSP groups established by the Department for Business, Innovation and Skills (BIS) appear to have concentrated on how the Government's NSP funding can be distributed to universities on the basis that a menu of options will be made available by institutions. This is a recipe for a complex postcode lottery.
"The NSP has been rightly described by ministers as a national scheme. As such students need clarity over what the NSP will deliver and reassurance that taxpayer funding will not be used to deliver different benefits according to where they study rather than according to need."
The chairman of Million+ and vice-chancellor of Bedfordshire University, Prof Les Ebdon, said: "There are concerns that Ministers want to link the NSP with A-level grades and pre-entry qualifications. It is well known that disadvantaged students often present with lower pre-entry qualifications and some mature students are accepted on to university courses with fewer formal qualifications.
"Any attempt to link the NSP with prior attainment will disadvantage many students from poorer backgrounds who will nonetheless go on to do exceptionally well at university."
He added: "Under the Million+ proposals, the NSP would provide the poorest students with an additional maintenance grant for the lifetime of their courses with applications and payments managed through Student Finance (the student loans company).
"This would be fair and simple for both students and universities and would avoid a national scheme degenerating into a discretionary and complex programme determined not by need but on the basis of where students study."
Demonstrations continued at the weekend over the Government's plans for tuition fees and the abolition of the Education Maintenance Allowance for poorer sixth-formers.
While in London, thousands took to the streets in a largely peaceful protest against Government cuts and university fee hikes on Saturday, 20 arrests were made in Manchester where a splinter group left an organised rally to protest at tuition fees and spending cuts and marched to the city centre.
Up to 4,000 protesters had gathered peacefully on Saturday to hear claims from union leaders that the Government was "betraying" young people, but trouble erupted when several hundred later broke through police lines.
The protest started in acrimony when NUS president Aaron Porter withdrew as he was surrounded by angry demonstrators who called for him to quit his post. There were reports of racist overtones to some chanting.
He needed a police escort of a dozen officers to the students' union building at Manchester Metropolitan University as around 150 people followed him and unsuccessfully tried to gain entry into the site.
Around 100 protesters were eventually contained by police in Deansgate near to the Hilton Hotel.
Those arrested – all men – were detained on suspicion of various public order offences. Two officers suffered minor injuries, one was bitten. Police said the breakaway group was intent on inciting violence and causing damage as intelligence suggested a number were armed with chefs' knives and one man arrested possessed razor blades.