The party said “freedom cuts both ways” when it comes to employers seeking a flexible workforce and that loopholes allowing bosses to tie staff to exclusivity deals should be closed down.
It comes after HuffPost revealed staff working on so-called ‘short hours contracts’ guaranteeing a set number of working hours per year were subject to many of the same conditions of much-maligned zero-hours deals.
The Lib Dems described the report as “deeply concerning”.
And a party spokesperson added: “I cannot reveal in advance what is in the Liberal Democrat manifesto, but we are determined to ensure that employers don’t get away with tying workers into exclusivity deals.
“If the employer wants the flexibility not to employ people as staff with all the ensuing obligations, then workers should have flexibility, too. Freedom cuts both ways.
“We are also really determined to stop employers forcing workers out of staff jobs to take on the role of being self-employed when really it is a sham and that worker is to all intents and purposes staff.
“We are deeply concerned that the Conservative Brexit government will water down worker rights even more by, for instance, scrapping the EU social legislation which does more than a lot of domestic legislation to protect the rights of workers.”
Documents suggested companies could exploit loopholes in the law to sidestep a 2015 ban on exclusivity clauses that stop staff working for other firms.
And they show how so-called ‘short hours’ contracts enable employers to demand staff to be at their “beck and call” - and potentially ask them to travel hundreds of miles for shifts.
The contracts have sparked condemnation from unions, with outsourced security staff at the University of London going on strike over their use this week.
Labour and the Conservatives did not respond to a request for comment. All the major parties are set to unveil their manifestos after next week’s local elections.
MPs last month condemned ‘gig economy’ contracts which prevented workers challenging their employment status and even attempted to make them liable for court costs if they did so.