Conservative MP George Eustice has resigned as agriculture minister, citing fears that Brexit could be delayed.

In a letter to Prime Minister Theresa May, he said: "It is with tremendous sadness that I have decided to resign from the government following the decision this week to allow the postponement of our exit from the EU.

"Since Parliament is now in direct control of events, I want to be free to participate in the critical debate that will take place in the weeks ahead.

"It has been an honour to work alongside so many talented individuals at Defra over the past five years. Defra has phenomenal expertise and, more than any other government department, has embraced the opportunities posed by our exit from the EU.

"I have particularly welcomed the chance to craft two new bills on farming and fisheries, which are the first for half a century, as we have prepared the ground to restore self-government in this country.

"I will vote for your withdrawal agreement when it returns to the house and I very much hope that the attorney general succeeds in securing final changes so that others might too.

"Although I campaigned to leave, I have always supported compromise to achieve a reconciliation in our country. Leaving the EU would represent an historic change and it is natural that some people will feel apprehensive.

"I have been open to the idea of using our existing membership of the EEA as an exit mechanism and I supported your approach outlined at Chequers when others did not.

"I have stuck with the government through a series of rather undignified retreats. However, I fear that developments this week will lead to a sequence of events culminating in the EU dictating the terms of any extension requested and the final humiliation of our country.

"I appreciate that you have been terribly undermined by those in Parliament who refuse to respect the referendum result. You have shown tenacity and resilience over the past year.

"However, what our country needs from all its political leaders at this critical juncture is courage, and we are about to find out whether Parliament has it.

"As a Defra minister, I have enjoyed good relations with the European Commission and with ministers from other member states.

"However, I do not believe that the commission has behaved honourably during these negotiations. They have deliberately made progress slow and difficult. They have stated in terms that they will refuse to even hold substantive negotiations on a future partnership until after we leave.

"If the position of Parliament is now that we will refuse to leave without an agreement then we are somewhat stuck.

"This is uncomfortable for everyone, but we cannot negotiate a successful Brexit unless we are prepared to walk through the door.

"We must therefore have the courage, if necessary, to reclaim our freedom first and talk afterwards. We must be ready to face down the European Union here and now.

"The absence of an agreement poses risks and costs for them too. We already know that in the event of 'no deal' the EU will seek an informal transition period for nine months in many areas and settlement talks could continue within this window.

"I will do what I can from the back benches to try to salvage this sorry situation and I hope that, when the moment comes, Parliament will not let our country down."

Rob Percival, head of food policy at the Soil Association said; As Minister of State for Agriculture, George Eustice helped re-frame agriculture policy, angling it towards a broader vision. He brought soil firmly onto the policy agenda, giving priority to environmental and animal welfare outcomes alongside food production.

“As a supporter of the horticulture sector, he contributed to the Edible Horticulture Roundtable, currently co-chaired by the Soil Association. His legacy includes plans for revitalised County Farms to support new entrants to farming and the 25 Year Environment Plan, which will soon be enshrined in legislation.

“The resignation of the Minister, weeks before the UK is scheduled to leave the EU, will undoubtedly be of concern for UK farmers. The Government must now move quickly to appoint a new Minister who can act as an effective advocate for the sector throughout the Brexit process, and who can secure Eustice’s legacy, pushing forward the policy agenda to secure a healthier and more sustainable farming sector.”

Country Land and Business Association (CLA) President Tim Breitmeyer said: “We are saddened to hear of George Eustice’s decision to resign as Farming Minister at the Department for Environment, Food and Rural Affairs. He has held the position since 2015, and has maintained a strong voice on behalf of the farming industry during that time.

“His farming background and first hand knowledge and experience have been invaluable in the many areas of his brief. The farming community has lost a key ally at this critical time for the industry, which faces significant uncertainty and change.”