Rural Labour MPs have called on the government to reassure worried farmers, in an attempt to quell the escalating row over inheritance tax on agricultural property. Thousands of farmers and landowners travelled to Whitehall on Tuesday to protest against the plans, which they say will force family farms to sell up in order to pay the new 20% rate on assets above a £1m threshold. At the rally, they booed the Labour party and said they had been betrayed and lied to. The environment secretary, Steve Reed, had promised farmers that he would not be implementing changes to agricultural property relief, and during the general election said reports that he was going to were “desperate nonsense”. Rachel Reeves, the chancellor, announced the changes to inheritance tax at the budget, saying they were a way to target rich people who put their wealth in land as a way of avoiding inheritance tax. Ministers say they expect only 500 farms to be affected, and insist that should not include small working family farms. Reed said on Tuesday it was “only right” to ask the “wealthiest landowners and the biggest farms to pay their fair share”. However, some Labour MPs in seats with a significant proportion of rural voters are urging the government to reach out to agricultural communities, rather than fight them over the tax. Terry Jermy, the MP for South West Norfolk, whose majority at the general election was just 630, told the Guardian he wanted the government to set up a hotline for concerned farmers. “I want to make sure family farms are not caught up in this unnecessarily,” he said. “It has been very difficult for farming in the last 14 years. We have to be very clear about the allowances and the different technicalities. I have called for a hotline for families to get advice and guidance – that is important.” He also called for taxpayer-funded farming subsidies to be distributed more quickly. “We need to make sure people can access the funding,” he said. Tonia Antoniazzi, the MP for the Welsh seat of Gower, added: “Family farms are the backbone of the industry ... farming is in these people’s blood. “The 100% rate of relief continuing for the first £1m of combined agricultural and business assets to help to protect family farms and businesses is most welcome, but I would appreciate an opportunity to discuss with the chancellor, the secretary of state for environment, food and rural affairs or the Treasury team how we can ensure that family farms that may come just over the threshold can continue to play their role in our country, and how we can support them through the change and avoid any unintended consequences.” Josh MacAlister, the MP for Whitehaven and Workington, also said that the government could introduce a tapering system for older farmers so they could be supported and not caught out by the surprise nature of the tax. Steve Witherden, the MP for Montgomeryshire & Glyndŵr, told the Times that the government should reveal its modelling “so everyone knows where they stand and then can plan accordingly”. More than 100 rural MPs are believed to have voiced concern to government over Treasury decision. Many have also been voicing discontent behind the scenes at the combative approach taken by the environment secretary, who has told farmers to “check the facts” and said they are “wrong” to be protesting against the changes. Some MPs have even begun to worry for their seats at the next general election. According to Countryside Alliance data, Labour now has 135 rural or semi-rural MPs. Many of these have very slim majorities. Speaking of the pain farmers are facing from the tax, the Labour peer Baroness Mallalieu said at the rally on Tuesday: “There are many of us in the Labour party, you may not believe it but there are, who see all that”. She warned Labour that it is “impossible to win a working majority without rural seats”.