More than 400,000 people have pledged their support to a petition supporting British food standards, within the last five days.

The petition urges the government not to allow imports of food that would be illegal for British farmers to produce.

The National Farmers’ Union’s food standards petition was launched in February, but saw a surge in support as celebrity chef Jamie Oliver announced signing the petition was “probably the most important thing [he has] ever done”.

The petition now has more than 450,000 signatures – most of which have signed since Oliver made the announcement on May 31.

The NFU has also been running a targeted social media campaign to maximise the reach of the petition and encourage supporters to sign up to the NFU’s ongoing Back British Farming campaign.

The Mail on Sunday launched its own ‘Save our Family Farms’ campaign in response.

NFU president Minette Batters said: “We are now at the eleventh hour. Winning this battle in the court of public opinion is where this now lies.

I applaud what Jamie Oliver has done, he clearly cares passionately about this cause. On Saturday, 30,000 people had signed up to our petition and now we have over 250,000.

“It’s been really powerful what he’s done on social media and we plan on keeping this momentum going. We are talking right across NGOs, farming organisations and with consumers to make this case.

“We are pulling on every lever on behalf of farmers to land this message and pave the way for a future that is about achieving carbon-neutral food by 2040.”