The news was revealed by the secretary of state for Environment, Food and Rural Affairs George Eustice during a press conference yesterday on the coronavirus pandemic.
The food industry has already said it is facing a challenge, as the loss of seasonal workers from overseas means there is a shortage of workers moving into the harvesting season.
At the beginning of April, the National Farmers Union called for a system to match workers with produce growers.
In March Eustice said there would be “sufficient resilience” of labour as many businesses were recruiting staff that had been “laid off” from other establishments in the food sector.
However, during the press conference, Eustice said there was a shortage of workers.
“We are acutely aware that we are about to start the British season in fresh produce in soft fruits and salads. We estimate that probably only about a third of the migrant labour that would normally come to the UK is here – and was probably here before lockdown,” he said.
“And we are working with industry to identify an approach that will encourage those millions of furloughed workers, in some cases, to consider taking a second job helping get the harvest in in June.”
He revealed that the food supply chain had also seen a drop in the number of staff off with sickness. At the peak, the numbers hit 20% three weeks ago, he revealed, but this was now down to 10% at the end of last week.
“The food supply chain has also seen a significant reduction in staff absence over recent weeks as staff who had been self-isolating through suspected coronavirus have returned to work,” he said.
However, Eustice did reveal that the international food supply chain was working well and there was not “any serious disruption” despite the pandemic, although he admitted there were some “isolated cases” of trade being disrupted, particularly for foods coming from India.
“But most of our trade with our near neighbours in Europe is continuing to flow normally,” he added.
On the panic-buying that was rife at the beginning of the crisis, Eustice said this had “quickly subsided”.
“Food availability now is back to normal levels and has been for several weeks,” he said.
He highlighted that supermarkets had introduced social distancing measures to protect both their staff and their customers and said it was “essential that shoppers respect these measures”.
Meanwhile, National Farmers Union vice president Tom Bradshaw said: "As the peak summer harvest approaches, we have been working closely with DEFRA to ensure a solution is in place for businesses to recruit domestic workers this summer.
“A dedicated website has been created by the government, and farm businesses and recruiters looking for staff are currently posting these vacancies on the site. We are expecting further news from the government this week on a drive to recruit people who want to help British farms.
“There will be thousands of vacancies opening up on farms across the country in the coming weeks and we have already seen a fantastic response from the public wanting to pick for Britain this summer.