The new higher education watchdog for England has promised not to impose quotas on universities to take on more poor students.
Sir Martin has promised to work in partnership with universities
Sir Martin Harris said universities shared his vision of widening access.
He also said he hoped they would raise £200m in bursaries for poor students when higher tuition fees - of up to £3,000 a year - came in from 2006.
Sir Martin, director of the newly formed Office for Fair Access (Offa), said "equality of opportunity" was his goal.
'Straight into students' pockets'
The £200m bursaries figure is twice the level the government said would be the minimum to safeguard the higher education of poorer students.
The money, paid "directly into students' pockets", would come from any increased tuition fees, Sir Martin told a press conference in London.
The bursaries would be needed to bridge the gap between the £2,700 government grant and the maximum fee of £3,000, he added.
Sir Martin, the former vice-chancellor of Manchester University, has published his guidelines for five-year "access agreements" with universities.
He is charged with ensuring students from under-represented groups have a fair chance of getting into higher education.
His remit from the government prevents him from making pronouncements on admissions, which remain for each university to decide.
But if they want to vary their fees from 2006 above the £1,200 standard level, they will have to negotiate with him an agreement setting out how they intend to "widen access".
Sir Martin said: "We are looking to the university sector to work with us."
Access agreements for 2006 should be in place by Easter next year, he added.
There are no set limits on the proportion of additional fee income universities are expected to use for bursaries.
The Offa guidelines say: "We expect that institutions whose records suggest they have furthest to go in attracting a wider range of applications, may wish to invest more than others."
Sir Martin promised a "light touch" in his dealings with them.
"This is a win-win situation. The students are going to benefit, particularly the poorer students.
"This isn't universities versus students; it's quite the opposite."
He added: "This is about making sure students with limited parental income are not discouraged from applying for courses they are qualified for."
Universities would, in turn, have access to more "talent".
Professor Ivor Crewe, president of the vice-chancellors' group Universities UK, said: "It is good to see that the guidance clearly reiterates that fact that Offa will be concerned with applications only, and that decisions on admissions will remain the prerogative of the universities."
It was critical that Offa did not take "a mechanistic approach", however.
The Conservatives have pledged to scrap Offa if elected, along with abolishing all tuition fees and offering students larger loans.
The shadow higher education minister, Chris Grayling, said: "Offa has nothing to do with improving standards in higher education; rather, it is the creation Labour backbenchers' blind prejudice.
"What academics, students and their families wanted to hear was the reassurance that educational attainment is still the only criterion for university entry.
"Instead they got the crude blackmailing of admissions tutors with cash for bursaries and the threat of fines for non-compliance with Old Labour posturing."
'Taking from the poor'
The Liberal Democrats also want to scrap fees, raising extra money through taxation.
Their spokesman, Phil Willis said Offa's proposals "take from the poor and protect the rich".
"Those universities that are already recruiting the largest number of poorer students will also have to provide the largest proportion of their income," he said.
This has been an issue for universities with large numbers of students from relatively disadvantaged backgrounds.
The University of East London, for example, has complained that it might have 10 times as many students qualifying for means-tested bursaries as a more elite university.
So it was among those that argued for a national bursary scheme. But the £200m estimated by Sir Martin is just the possible total - each university will be operating its own scheme.
Some have said they will offer more than £300, perhaps spending 30% of the extra.
Cambridge, for example, has said it will upgrade its £1,000-a-year bursary scheme so that about one in 10 undergraduates get help equivalent to basic living costs - estimated at between £5,000 and £6,000 per year.