• Dutch populist leader Geert Wilders described the European Union as a "monster" that must not be given more decision-making power by its member states.
• Rejecting the idea of European-wide taxation and ever-greater political union, Wilders told CNBC that the region needed less integration, not more.

Dutch populist leader Geert Wilders has described the European Union as a "monster" that must not be given any more decision-making power by its member states.

Rejecting the idea of EU-wide taxation and ever-greater political union, Wilders told CNBC that the region needed less integration, not more.

"Europe is a kind of monster, the European Union, if you give it more power they only want more and they won't give it back," the leader of the Party for Freedom said Sunday.

Wilders argued that the economic cooperation that underpins the EU had morphed into deeply embedded political integration between its 27 members.

"It's too late to end it but please, let us take some of the powers back to the capitals, like [those] for immigration," he told CNBC's Steve Sedgwick at the Ambrosetti Forum in Italy this weekend.

"All of the politicians who are really out of sync with the electorate in Europe say, 'we want more integration,' but the people don't want that, they want their own [domestic] issues to be solved."

"I believe that the majority of the decision-making should be in the nation-state and the national parliaments," Wilders — an increasingly influential figure in European far-right politics — added.

His Party for Freedom (PVV) has become part of the political mainstream in recent years, upsetting the status quo in the Netherlands and beyond.

The rise in the party's popularity culminated in the PVV winning a landslide victory in the Netherlands' general election last November, taking 35 seats of the 150-seat Dutch House of Representatives.

The PVV had to look for coalition partners in order to form a majority government, however, and a deal was only reached when Wilders agreed he would not be the country's new prime minister. The four parties within the coalition finally settled on the former head of the Netherlands' intelligence service, Dick Schoof, as PM.

There's no doubt that Wilders remains a central and driving force in Dutch politics, however, and his anti-immigration and euroskeptic stance has caused a headache for the European Commission, the executive body of the EU.

The EU's goal has long been "ever closer union," but a number of increasingly fractious member states — anxious about immigration and a lack of a cohesive EU-wide policy on the issue — have started pushing back.

Despite being one of the most vociferous critics of the EU who has campaigned for the Netherlands' to leave the bloc, Wilders told CNBC he has now abandoned that position, saying it was "too late" for a so-called Nexit.

Instead, Wilders wants an "opt-out" policy when it comes to EU-wide asylum rules and his party has said it will pursue the "strictest-ever admission policy" when it comes to immigration.

"It's very important to try to toughen up our borders, but at the end of the day, we have to do it nationally," he noted Sunday.

"We have to be in charge of our own immigration rules, of our own asylum rules, of our own border controls. Any nation without being able to decide who is welcome in the home is not really a nation," he added, but did not specify any details for his proposed opt-out system. The European Commission declined to comment on Wilders' remarks when approached by CNBC on Monday.

Populist and nationalist parties have made large political gains across Europe over the last decade as the region has experienced a large influx of migrants from the Middle East and sub-Saharan Africa, including those fleeing conflict and persecution and seeking asylum in the EU, and others seeking better economic prospects.

The leaders of these parties say the EU has failed to adequately deal with what they describe as a migration "crisis," and say the rise in their popularity shows voters want politicians to curb immigration and prioritize national security, health care, education, jobs and housing.

Critics of these parties say they are divisive and looking to sabotage European integration and unity, however. They also point out that the birth rate in many European countries is falling and the region needs migrant workers. The EU, meanwhile, has had to tread a fine line between accepting the results of democratic processes, and the rise of euroskeptic sentiment.

The EU completed reforms to its migration and asylum policy earlier this year in an effort to ensure a system of "mandatory solidarity" that sees all member states take their fair share of asylum seekers. It came after a number of countries, particularly those in the southern Mediterranean area, argued that they had been left to shoulder an influx of migrants arriving in the region by boat, alone.