Prime Minister Boris Johnson says the UK must see free trade agreements ‘not as threats but as opportunities’.
It comes as it is understood the UK is preparing to offer Australia a trade deal that would see tariffs and quotas phased out over 15 years.
The deal has been described as potentially ‘devastating’ by NFU Scotland.
The farming union has warned the move could see more produce, particularly beef and sheep meat, coming into the UK.
They fear it will lower standards and larger farms in Australia will undercut farmers in Scotland.
NFU Scotland chief executive Scott Walker said: “No consultation has been had with NFU Scotland on such proposals and any such deal would be wholly unacceptable to Scottish farmers and crofters.
“The impact on family farms of food produced to lower standards than those set here would be devastating.”
But Johnson said: “We see a global future for this country.
“I do think that free trade deals present a fantastic opportunity for our farmers, for our businesses of all kinds.”
Scotland’s rural affairs secretary, Mairi Gougeon, has written to UK international secretary Liz Truss, saying a deal must not be signed that would allow imports of food produced “to a lesser standard”.
She wrote: “At a time when UK agri-food producers are facing significantly greater barriers to trade with Europe – the sector’s largest export market – it would be incomprehensible for the UK Government to sign up to a trade deal that would facilitate mass imports of Australian agri-food produced to a lesser standard.”
She added: “A trade deal that liberalises tariffs for Australian farmers, to put it bluntly, will put UK farmers out of business.”
NFU Scotland president Martin Kennedy warned the free trade deal would be a “deep betrayal” by the UK Government.
He added: “Unfettered access for a country like Australia – that would be really concerning.
“That puts under threat, not only prices of what our products are but our environmental standards and our animal welfare standards.”
However, the farming union that represents Australian farmers says any increase in meat coming from the country to the UK would be driven by demand.
Fiona Simson, president of the country’s National Farmers’ Federation (NFF), said: “The volume of Australian red meat to the UK in the context of the UK’s total red meat imports and Australia’s total exports, is very, very small.
“The aim of any free trade agreement is to provide both parties options. Australian red meat producers would like to have the option to export to the UK if and when the UK needs it.”
The NFF says that currently around 0.15% of beef exports from Australia go to the UK, with 14% of the UK’s sheep meat imports coming from the country.
Some other industries have been pushing for a better deal with Australia, including the whisky industry, which sees the country as a potentially growing market.
Downing Street has said “negotiations are still ongoing” but insisted that farmers would be protected in any deal.
It comes after members of the cabinet, believed to be split on the idea of an FTA with Australia, met in London.
The worry for some is that other countries, including the USA and Brazil, will ask for similar demands in any future agreements.
The Scottish Conservatives say they are “engaging constructively with the UK Government, key stakeholders and the farming community” and will “wait to see the details of any proposed deal”.