A report by the House of Lords European Union select committee is calling on the government for clarification on post-Brexit funding and UK involvement in the EU's Erasmus+ youth study and training scheme.
Peers are particularly concerned that losing access to the programme's funding would deny disadvantaged young people the chance to study and train abroad.
These groups have the most to gain from the programme and are most in need of funding, particularly those with disabilities or in need of medical support, says the report.
It details research by Universities UK, which found that students who study or train abroad are 20 per cent less likely to be unemployed six months after graduation and one in three Erasmus+ work placement students are offered a job at their host company when they graduate.
Among those to give evidence to the committee was Association of Colleges representative John Latham, who told peers that vocational, education and training "mobility" opportunities "would stop in their tracks" without Erasmus+ funding.
Such opportunities could then be restricted only to "those who can afford to go", he added.
The peers' report states: "We were struck by the stark warning that mobility opportunities for people in vocational education and training would 'stop in their tracks' without Erasmus funding, and we are particularly concerned that losing access to the programme would disproportionately affect people from disadvantaged backgrounds and those with medical needs or disabilities."
Last month, the Department for Education published a technical notice stating that if the UK leaves the EU with a deal in place then funding for the current programme, which runs until 2020, will be unaffected.
In the event of a no-deal Brexit however, the UK government will need to negotiate with the European Commission, and possibly separately with EU countries, to ensure those applying after Brexit on 19 March 2019 can still receive funding.
The UK's involvement in Erasmus+, which is also accessed by teachers and youth workers, after the current programme expires in 2020 is also in doubt.
The committee is calling on the government to clarify funding arrangements, and to work with the EU to avoid disruption to the scheme in a no-deal Brexit scenario.
In addition, peers want the government to seek to participate in the next phase of Erasmus, as an associated third country. If this is not possible peers want the government to set up an alternative scheme, although it concedes this is unlikely to be as successful as Erasmus.
"The Erasmus programme has played an important role in increasing opportunities for young people and teachers in the UK to study, train, teach, and gain work experience abroad," said committee chair Lord Jay of Ewelme.
"The UK has received substantial amounts of funding from Erasmus but the value of participating in this programme cannot be measured simply in financial terms. Erasmus improves people's employment prospects, increases opportunities for people from disadvantaged backgrounds, and facilitates international collaboration in the field of education."
The Department for Education has been contacted for comment.