European universities have failed to improve student opportunities, an obligatory part of the Bologna Process, and must act now if they are to avoid the entire exercise becoming a "superficial redesign" of higher education.
The warning has been issued by the European Students' Union (ESU), which is urging education ministers to force universities into action ahead of next year's deadline to meet the terms of the process.
Bologna aims to create a European Higher Education Area by 2010 within which higher education is equitable, flexible and competitive internationally.
But the ESU claims in a report, Bologna with Student Eyes 2009, that despite progress on structural reforms, issues such as widening participation and student mobility have been largely neglected, leaving "a hole at the centre of the process".
Ten years since the process was drawn up, European students still face huge barriers to learning linked to their socio-economic background and home life, the ESU says.
Attempts to increase mobility across European institutions have also failed, it suggests.
The report comes as a student survey from the European Commission found that 11 per cent of students had planned to study abroad but had given up on the idea.
The ESU has said that delivering Bologna now requires a change of approach, with ministers called upon to draw up national plans for action.
Ministers are due to meet this week in Belgium to discuss the progress of the Bologna Process. The ESU's chair, Ligia Deca, has warned them not to "cover up" the inadequacies with "new and superficial attractions".
Aaron Porter, vice-president for higher education at the National Union of Students, said UK universities still had a long way to go to meet the requirements of Bologna.
"From a UK perspective, I think implementation of the whole Bologna Process is patchy," he said. "There has been slow progress since the London summit two years ago. In the area of mobility, I don't think universities have made nearly enough progress."
He added: "UK universities are often complying with the Bologna Process to tick boxes rather than having it fully integrated into the institution."
Ms Deca said the ESU report provided a "road map" for action across Europe. "Only in this way will students once more come to have faith in a process where, so far, delivery has failed to keep pace with political promises," she said.