The growth of anti-EU parties in the European Parliament elections in May could “paralyse” the bloc in a range of policy areas, a stark report seen by The Independent has warned.

Nationalist, eurosceptic, and far-right parties could bring about a “qualitative change” in the union after winning a third of seats, according to the European Council on Foreign Relations, a pro-EU think tank.

The result would give the populists significant influence in the union and the ability to block some legislation, says the study, which is set to be released on Tuesday.

The parties would be able to appoint the chairs of a third of European Parliament (EP) committees and block the body from triggering so-called “Article 7” procedures against rogue member states that flout the rule of law – as it did with Viktor Orban’s Hungary last year.

Even more significantly, unless all the other political groups consistently vote together, populists might also be able to block the election of the next European Commission president to replace Jean-Claude Juncker, shape EU law, and influence the union’s budget.

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

The Eurosceptic votes could also help derail already controversial international agreements – such as a possible free trade deal with a post-Brexit UK.

“Simply put, winning a certain number of seats will give anti-European forces influence over key processes and decisions,” the report says.

“Judging by what many of them have campaigned for, anti-European parties could use this increased share of seats to obstruct the EP’s work on foreign policy, eurozone reform, and freedom of movement, and could limit the EU’s capacity to preserve European values relating to liberty of expression, the rule of law, and civil rights.

“Winning more than 33 per cent of seats would enable them to form a minority that could block some of the EU’s procedures and make the adoption of new legislation much more cumbersome – with a potentially damaging impact on the content of the EU’s foreign policy, as well as on the EU’s overall institutional readiness and its political credibility to take initiatives in the area.”

The report looks at polls from across the continent and finds that under current projections the far-right is set to make advances – mirroring or exceeding those it has made at a national level since the last elections in 2014. It says “the far right and right-wing Eurosceptics will, if current polling is accurate, rise from 23 per cent to 28 per cent” with this potentially rising to around 30 per cent once the campaign is underway.

“They could even gain more than 30 per cent of seats if their popularity continues to grow or if some of the fringe members of the mainstream join them. If they cross the one-third threshold, this would signify a qualitative change in the EU,” the report adds.

In certain policy areas, dissent from the mainstream by the eurosceptic far-left – such as on trade, sanctions, and foreign policy – could also make passing legislation difficult.

Though the assorted eurosceptic parties across the continent have struggled to form a coherent alliance, when it comes to votes in parliament they have often voted in a similar direction. Despite being spread across disparate political groups, most populist forces voted against sanctions against Hungary in a crunch vote last year.

There are also increasing moves to try to unite the groups – such as the plan for an “anti-immigration axis” proposed by Italy’s de facto leader Matteo Salvini. Far-right US figure Steve Bannon has also unveiled plans to unite the groups, though it is unclear whether he will be successful.

“The warning in this report, that anti-European parties are gaining strength and could paralyse the EU, should concentrate the minds of pro-Europeans,” said Mark Leonard, director of the European Council on Foreign Relations.

“They must not become trapped into becoming defenders of the status quo in Europe or allowing the election to become a referendum on the issue of migration – which is exactly the battleground that the anti-Europeans want.

“Instead, pro-Europeans need to unmute the silent majority by fighting different elections that Europe’s different publics will vote on – such as the climate change election, the ‘Facebook’ election for those concerned for their data and privacy, the election for those worried about Russian aggression, the prosperity election for those worried about stalled living standards, the rule of law election for those worried about democratic backsliding, and the ‘saving Europe’ election for the EU’s most ardent defenders.”