David Cameron has hammered home the economic arguments for remaining in the European Union – as politicians and activists of the main Remain-supporting parties stage a day of action to save Britain’s membership of the bloc.

The Prime Minister unveiled a poster bearing the Treasury’s claim that every family would be £4,300 worse off in the event of Brexit and warned that a vote to leave the EU could tip the British economy back into recession.

A recession would be the "last thing our economy needs," Mr Cameron said.

Mr Cameron also argued that the decision being put to the British people is “bigger than party politics”.

Also on Saturday, Labour leader Jeremy Corbyn will lay out his vision for remaining in the EU in a speech at the QEII centre in Westminster, London, Liberal Democrat leader Tim Farron will lead a campaign in Kendall and Green Party MP Caroline Lucas will make her case in Brighton.

Mr Corbyn in particular is stepping up after having been urged by some of his MPs to take a greater role in defending membership of the EU.

Jo Cox, Labour MP for Batley and Spen, yesterday told The Independent that Mr Corbyn should use his “unique voice” as a sometime-Eurosceptic to convince wavering Labour voters.

The Labour leader yesterday urged young people to register to vote for the referendum, warning that those who neglected to do so would be left with “no voice”.

Jeremy Corbyn is campaigning for Britain to remain in the EU (Getty)

In total, Remain campaigners say they will be staging 1,000 events led by around 6,200 campaigners from Britain Stronger in Europe. The campaign’s organisers hope the push will help their side open up a lead in the polls – which have been stubbornly close in recent months.

Mr Cameron sought to emphasise the cross-party nature of the campaign in his speech on Saturday – a risky strategy reminiscent of some aspects of the Better Together approach during the Scottish Independence Referendum.

What's the European Parliament ever done for us? Show all 5 1 /5 What's the European Parliament ever done for us? What's the European Parliament ever done for us? A cap on the amount of hours an employer can make you work The Working Time directive provides legal standards to ensure the health and safety of employees in Europe. Among the many rules are a working week of a maximum 48 hours, including overtime, a daily rest period of 11 hours in every 24, a break if a person works for six hours or more, and one day off in every seven. It also includes provisions for paid annual leave of at least four weeks every year Getty Images What's the European Parliament ever done for us? Helping the people of Britain to avoid smoking In 2014 MEPs passed the Tobacco Products Directive strengthening existing rules on the manufacture, production and presentation of tobacco products. This includes things like reduced branding, restrictions on products containing flavoured tobacco, health warnings on cigarette packets and provisions for e-cigarettes to ensure they are safe What's the European Parliament ever done for us? Helping you to make the right choices with your food Thanks to the European Parliament, UK consumers have access to more information than ever about their food and drink. This includes amount of fat, and how much of it is saturated, carbohydrates, sugars, protein and so on. It also includes portion sizes and guideline daily amount information so people can make informed choices about their diet. All facts must be clear and easy to understand What's the European Parliament ever done for us? Two year guarantees and 14-day returns policy for all products Consumers across the EU have access to a number of rights, from things which are potentially very useful, to things which used to be annoying. For example, shoppers in the UK receive a two-year guarantee on all products, and a 14-day period to change their minds and return a purchase, these things are useful www.PeopleImages.com-licence restrictions apply What's the European Parliament ever done for us? Keeping your air nice and fresh (and safe) Believe it or not, although the situation is improving, some areas of the UK have appalling air quality. A report by the Royal College of Physicians released on 23 February says 40,000 deaths are caused by outdoor air pollution in the UK every year. Air pollution is linked to a number of illnesses and conditions, from Asthma to diabetes and dementia. The report estimates the costs to British business and the health service add up to £20 billion every year

“We’ll see the effects of this referendum in our lives: the jobs we do, the opportunities our children have, the public services we rely on, the prices we pay, and the bills that land on our doormats,” he said.

International Monetary Fund Managing Director Christine Lagarde on Friday warned against the effects of Brexit (International Monetary Fund)

“This is a day unlike any other: politicians of every stripe taking to the streets with the same message. Because we face a vote unlike any other, one which will shape our country for decades – even generations – to come," Mr Cameron said.

“This is bigger than party politics. Its effects will last longer than our lifetimes. So we are saying with one voice: make sure Britain is stronger, safer and better off – and vote to remain in a reformed European Union.”

Over recent days the Leave camp has been running stalls around the country, with key figures taking their campans to the road. Former Mayor of London Boris Johnson paid a visit to Cornwall, where he warned against migrants coming to Britain without a job offer.

On Saturday, Mr Johnson will be speaking in the South-west while the Grassroots Out campaign is mounting a nationwide blitz with events across the country.

They include a rally in Chester addressed by Conservative former cabinet minister Owen Paterson and Ukip migration spokesman Steven Woolfe.

Mr Paterson will say: “If we vote to remain, we will be consigning ourselves to being a colony of an EU Superstate, with more integration and increasingly diminished British influence".

Top-ranking institutional economists however issued warnings about Brexit this week.

Bank of England governor Mark Carney said the event could cause a sharp collapse in the value of the pound, while the IMF’s managing director Christine Lagarde warned the effect of Brexit on the British economy ranged from “pretty bad to very, very bad”.