A committee of MPs has lambasted Uber’s contracts with drivers as “gibberish” and “almost unintelligible” as the company attempts to ensure its drivers remain self-employed.

Frank Field, chair of the work and pensions select committee that is carrying out an investigation into the so-called gig economy, said: “Quite frankly the Uber contract is gibberish.

“They are well aware that many, if not most, of their drivers speak English as a second language – they recently lost a court case trying to escape Transport for London’s new English testing rules for private hire drivers – yet their contract is almost unintelligible.”

The gig economy refers to the growing number of workers classed as self-employed contractors without access to sick benefit or holiday pay.

Publishing full details of Uber’s contract terms, along with those for the takeaway courier firm Deliveroo and Amazon, Field said all three used some kind of “egregious clause” which attempted to prevent people challenging their “self-employed” designation, although neither Uber’s nor Amazon’s contract went as far as Deliveroo’s, in the committee’s view.

“The way they work looks in most ways an awful lot like being employed,” Field said. “These companies parade the “flexibility” their model offers to drivers but it seems the only real flexibility is enjoyed by the companies themselves. It does seem a marvellous business model if you can get away with it.

“My worry is that as a result these companies contribute little to the public purse or our social safety net. They are not paying sick leave, national living wage, or contributing to pensions. Yet it seems likely that their employment practices will lead more people to need taxpayers to pick up these costs.”

Uber said it was in the process of revising its contracts into plainer English and its contract did not prevent anyone challenging their employment status.

A spokesperson said: “Almost all taxi and private hire drivers in the UK are self-employed. We’ve always been clear to drivers who use Uber that they are self-employed and free to choose if, when and where they drive with no shifts, minimum hours or uniforms. There is nothing in our terms to stop anybody challenging this. In fact a small group of drivers recently took us to an employment tribunal claiming they’re not self-employed.”

The employment tribunal ruled that its drivers are “workers”, with the right to holiday pay and the national minimum wage, rather than self-employed contractors. However, Uber has won the right to appeal.

Deliveroo told MPs it was removing a clause in its courier contracts which demands its riders agree not to challenge their self-employed status in court.

Dan Warne, managing director the food delivery service’s UK and Irish business, wrote to MPs saying the clause would be removed “within the coming weeks” after being criticised for trying to prevent workers from claiming the employment rights due to them.

However, Warne’s letter makes clear that the company, which is facing several legal challenges over the status of its couriers, still considers its riders self-employed contractors. A spokesman for Deliveroo added that the clause had never been enforced.. ”

An Amazon spokesman said: “Amazon Flex offers people the opportunity to make great earnings working on their schedule to deliver Amazon parcels. The majority of people participating in Amazon Flex already have full or part time jobs and use the programme to top up their income, with 70% working 10 hours or less a week, in 1-4 hour delivery blocks, and earning £12 to £15 an hour.

The committee said: “Whether any of these clauses are legally enforceable is perhaps not the point: the intention appears to be to put people off challenging their status, including going to court, and trying to obtain employment rights that may be due to them.”

• This article was amended on 6 April to add further detail on the committee’s comments about Uber, Amazon and Deliveroo contracts.