The former Tory leader claimed the EU may cease to exist if the crisis is not resolved, and that the UK will play a key role as “the future migration crisis is the one that will break the Schengen zone, the EU, and the mainstream leadership of Europe” if it is left to develop.
With the population across the Middle East and Africa expected to double over the course of 30 years – an increase of one billion people according to Sir William, he warned the crisis could overwhelm Europe and may lead to Ms Le Pen coming to power in years to come.
Writing in the Telegraph, Sir Hague warned: “Those who imagine that the populist tide is now defeated will be in for a terrible shock unless people feel much better about the future in a few years’ time than they feel today.”
He maintained that “populists, including Marine Le Pen, will be back with a vengeance”, if Mr Macron refuses to take action.
Mr Macron, France’s youngest ever president, is a strong supporter of the European Union.
The 39-year-old walked out to the EU’s Anthem of Europe at his victory rally and used his first speech as president-elect to profess his support for the bloc.
Speaking to the public, he said: “I’ll defend France, I’ll defend Europe, and will strengthen links between Europe and its people.”
Sir William was keen to highlight the initiatives Britain and France has previously embarked upon together to take in migrants from “failed states”, but that “other Europeans need to do much more”.
While “there are no simple answers” to the growing crisis, Mr Hague urged European countries to “destroy people-smuggling operations and deter people from risking their lives in crowded boats that are not sea worthy”.
The former Tory leader downplayed Mr Macron’s victory, claiming “it was an unenthusiastic landslide” because the independent candidate was elected “for what he is not”.
Sir William added: “Rejection of established leaders and policies was the real story of this election, in a country with slow growth, high unemployment, excessive taxes, obstructive trade unions and growing cultural divisions.”