LONDON, May 28 (Xinhua) -- More than 100 organizations in Britain representing thousands of farmers and the country's food supply chain sent a Brexit manifesto Monday to Prime Minister Theresa May.

With little more than 10 months to go before Britain ends its membership of the European Union, the manifesto emphasizes the importance of ensuring the departure from the EU does not undermine the food production and supply sectors in Britain.

The biggest fear in the farming industry is the heavily reliance on thousands of European nationals who traditionally head to farms across Britain every crop picking season to harvest fruits and vegetables.

The concern is that the supply of casual labor will be cut off once Britain parts company with the EU.

Leaders of 100 organizations have put their names to the manifesto setting out the key principles that can help ensure Brexit is a success for the supply of food in Britain. It calls on May's government to publish a white paper setting out its immigration plans as a matter of priority.

The manifesto said the significant number of EU nationals employed meant it was vital the government ensures a continuing, adequate supply of permanent and seasonal labor before and after Britain leaves the EU in March 2019. The industry cites difficulties in recruiting enough people in Britain for crop-picking work.

The UK Food Supply Chain Manifesto has been drawn up by organizations representing farmers producing the raw ingredients and their suppliers, right through to manufacturers and retailers. It sets out the need for positive outcomes on trade, labor, regulation and domestic agricultural policy.

The manifesto has been sent to the Prime Minister as well as other key members of her cabinet by the president of the National Farmers Union (NFU) Minette Batters.

Batters said: "Today we are presenting a united voice as a food and farming sector worth at least 112 billion pounds (150 billion U.S. dollars) to the UK economy and employing around 4 million people."

Batters, a full-time working farmer and the first female head of the NFU, added: "In the manifesto we warn, as a collective, that a Brexit that fails to champion UK food producers, and the businesses that rely on them, will be bad for the country's landscape, the economy and critically our society."

"As we enter this critical period in the Brexit negotiations, the signatories to this manifesto will be looking to government to ensure its objectives are aligned with ours to ensure British food production gets the best possible deal post-Brexit," she said.