Jeremy Corbyn is to speak to the organisers of the Glastonbury festival about their use of zero-hours contracts, his spokesman has said.
The Labour leader appeared on stage at last month’s event to speak about employment rights among other issues.
Most of the workers hired, from around Europe, to clean up after the festival were reportedly laid off early.
But organisers said the litter pickers had “temporary” agreements which guaranteed at least eight hours work.
In a statement, Glastonbury festival said the “unusually dry” weather was partly responsible for reducing the amount of work after this year’s festival.
According to the Independent, about 700 workers had travelled to Somerset from the Czech Republic, Spain, Poland and Latvia to help with the post-festival clean-up operation, on zero-hours contracts.
They were reportedly promised two weeks’ paid work but were laid-off after two days because there was less litter than expected, leaving them stranded and out of pocket.
In a video filmed by the Independent, a supervisor is heard telling sacked workers obstructing vehicles in protest that they should be grateful for two days’ work.
Mr Corbyn used his appearance on the festival’s Pyramid stage to say young people should not have to “accept low wages and insecurity as just part of life”.
Asked whether he would boycott Glastonbury in future, Mr Corbyn’s spokesman said: “Jeremy and the Labour Party have taken a very strong stand against the use of zero-hours contracts and the exploitation of migrant and other workers, and we would take that view wherever it happened.
“How Glastonbury runs its event and runs its finances is entirely a matter for them.
“But these contracts should not be in place and shouldn’t be used.
“We oppose them, and next time we are in government we will ban them.”
Asked whether Mr Corbyn would raise the issue with organisers next time he visits the festival, the spokesman said: “He is happy to raise it right now.
“This kind of contract and these kinds of employment conditions are unacceptable.”
In a statement, Glastonbury festival denied they had used zero-hours contracts, saying: “We would like to state that Glastonbury festival’s post-event litter picking team are all given temporary worker agreements for the duration of the clean-up.
“The length of the clean-up varies considerably from year to year, based largely upon the weather conditions before, during and after the festival.
“This is something the litter pickers – many of whom return year after year – are made aware of in their worker agreements (which assure them of a minimum of eight hours’ work).
“This year was an unusually dry one for Glastonbury. That, coupled with a fantastic effort from festival goers in taking their belongings home, meant that the bulk of the litter picking work was completed after 2.5 days (in 2016, a very wet year, the equivalent period was around 10 days).”