As many as 250,000 students will be denied college places from September under plans to cut #163;115 million from further education and sixth-form budgets.
The publication of college budgets just before the general election will be deeply embarrassing to ministers, who provoked the cuts by capping further education spending earlier this year.
The Opposition parties are certain to make election capital out of a threat to post-school places.
Labour has already claimed the figures as evidence of ministerial incompetence, but was forced to concede little immediate action could be taken to reverse the cuts. The Liberal Democrats said ministers were trying to defer the cuts news until after the election.
The plans published this week by the Further Education Funding Council are a double blow to colleges, drastically reducing cash for student places.
Principals and union leaders warned courses would have to be cut and jobs lost under provisional budgets sent to colleges this week.
Some 86 per cent of colleges face cuts. Sixth-form colleges, art and design and performing arts colleges will be hit hardest - none will avoid a cut in funding.
Colleges were still assessing the full impact of their budgets, but principals warned that costly courses crucial to Britain's economic recovery like construction, science and engineerin g would be affected. Adult education will also bear the brunt of the cuts.
Colleges applied for cash to provide just over 1.3 million full-time college places from September - roughly equivalent to 3.93 million full and part-time students. But they were allocated funding for only about 1. 2 million full-time places, leaving colleges faced with turning up to 258,000 people away.
There are also severe cuts to funding for the places that remain. Overall, colleges have to make savings of 7.6 per cent after inflation.
One principal, Hilary Cowell at Filton College, Bristol, said she was facing 14 per cent savings. She said: "I don't think we can sustain our level of offers given the savings we have to make."
Labour was quick to attack the funding plans, saying that its Welfare to Work proposals launched this week, would more than cover the cuts in student numbers.
Shadow education minister Bryan Davies criticised the Government's "total inability" to predict rising student numbers. He said: "The contrast can now be clearly seen. It's Welfare to Work with Labour and fewer students with the Tories."
He added that a new government would have no power to reverse this year's settlement.
Liberal Democrat education spokesman Don Foster claimed plans for on-going college "efficiency gains" represented cuts of #163;400 million over the next four years. He added: "All the Government was trying to do was to defer the bombshell until after the election and they have been found out."
This week's budgets proposals are the legacy of ministers' decision earlier this year to end funding for college expansion - leaving a gap between the number of students taught this year, and the number of places to be funded under the new capped budget last year. Ministers have maintained they were not kept informed about the bill for expansion.
An FEFC spokeswoman insisted that some colleges would recruit more students than in their budgets, and would absorb the cost, a claim rejected by college leaders.
John Brennan, FE development director at the Association of Colleges, warned: "It's very likely that some institutions will have to consider very carefully whether they remain viable."