Thousands of British workers who responded to a nationwide appeal to help pick fruit and vegetables on farms have rejected job offers, it has emerged.

As hundreds of workers are being flown in from Romania to pick lettuce and asparagus, specialist recruitment firms revealed that fewer than 20% of the applicants were either willing or able to take up roles on the farms.

The Alliance of Ethical Labour Providers said it had received 36,000 applications of interest but only 6,000 had opted for an interview for a role.

Concordia, one of the three recruitment companies in the alliance, said: “To date 900 people have explicitly rejected the roles we have offered and 112 have taken up our offer of a role on a UK farm.”

It said the main barriers were the length of the contract, location of the farm, and inability to work full-time because of care responsibilities.

Another recruitment firm in the alliance, Hops, said only 9% of those who had completed the recruitment process were eligible for the job.

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“Some are saying they cannot commit to 40 hours a week, some can only commit for a few weeks whereas some roles can be full time for eight weeks and some can be up to six months,” said Sarah Boparan, the operations director at Hops.

She said that even though they were not able to hire all who applied, she felt there was an education process under way about farm work that could have a lasting impact after Brexit, when Conservative party plans will put a block on low-paid and low-skilled workers coming to the UK from abroad.

“We are so pleased to see so many people apply and so thankful they have responded to the call to support agriculture in this country and we appreciate their patience as some of the crops are not yet ready and new offers will be going out,” she said, adding that peak recruitment would not really start till the end of May for most farms.

Several people who said they had responded to the government-backed appeal complained about the barriers to taking up the posts, particularly the on-site accommodation.

One man who contacted the Guardian, who lives in Norfolk and wanted to commute to a job locally, where there are many farms, said: “Some of the jobs require you to live on-site. It doesn’t make it easy at all. If we really need to be picking all these vegetables, they don’t make it very easy. I can’t move; I have a family.”

Gary Leshone, 35, who used to work in fishing in Grimsby, launched his own personal recruitment drive when the national Feed the Nation appeal, backed by the environment secretary, George Eustice, was launched three weeks ago.

He managed to get 150 volunteers who were willing to cross the country to Herefordshire and to live on-site for six months.

“I contacted farmers individually and initially I was told by one farmer he’d take as many workers as he could get, so I went on radio and social media and got 150 people. I know I could probably find 1,000 to 2,000 here because people are out of work.”

He was then told by the farmer that he needed a gangmaster’s licence if he was going to place that many workers on the market, which he was told would take 10 weeks to obtain.

“By that time the fruit and veg will have rotted and the borders will probably be reopened,” he said.

Underlining the confused messaging surrounding the sudden recruitment drive, Hops pointed out that the Gangmaster and Labour Abuse Authority was doing checks and handing out gangmaster licences within five days because of the crisis.

“The Romanians coming in are just like us, looking for work to feed their families themselves, but if they need 90,000 people and you have all these British people unemployed and the government has to pay out universal credit, it’s just ridiculous. The government should do more to sort this out,” said Leshone.

Recruiters appealed for patience among British hopefuls, pointing out that the peak season started from May and there would be “thousands of roles available for people who are in need of a job”.

There was controversy in Romania after photographs emerged of crowds gathering in regional airports for flights to Germany, which, like the UK, is also suffering a labour deficit. Questions are being asked in Romania as to how workers could leave to help ease other countries’ demand for fresh food when much of Romania is in strict lockdown.

G’s Fresh, one of the UK’s biggest salad growers, which has chartered two of the six planes from Bucharest, said it had recruited 500 British workers so far.

“We’re really pleased with how the recruitment campaign is going, but it is important that we have got these people from Romania. These are key skilled workers who were with us last year. We need experienced people who can make sure everyone is safe and knows what to do,” Beverley Dixon, the company’s HR director, told Eastern Daily Press.

Romanian workers travelling to the UK were given masks and sanitiser before boarding and would be be quarantined in small teams before full deployment, G’s Fresh said.