Denmark has begun erecting a 43.4 mile (70-kilometer) wall along its border with Germany in a bid to keep out wild boars.

The move aims to prevent the spread of African swine fiver, which could put the country's pork industry at risk.

Work on the fence, which is expected to be up to 5 feet (1.5 meters) tall, began today in Padborg, a city 136 miles (220 kilometres) southwest of Copenhagen.

Workers pictured while erecting a fence along the Danish-German border in the city of Padborg, Denmark, southwest of Copenhagen

The setup of the fence along the border, which is being designed to prevent wild boars from entering Denmark

The wall was authorised by Danish lawmakers after the government announced that Denmark's pork exports to non-European Union countries could be affected by African swine fever.

The industry is worth £1.2 billion (11 billion kroner) annually.

In 2016, total Danish pork exports were worth about £3.46 billion (30 billion kroner).

Unlike swine flu, African swine fever doesn't affect humans but it can be deadly for domestic and wild boars.

This can in turn cause massive losses for farmers.

Critics say the £3.50 million (30 million kroner) fence will harm wildlife and is a symbolic gesture tackling a largely non-existent problem.

Danish officials have admitted that wild animals could, in theory, still pass through the gaps in the fence where it crosses highways, roads and streams.

No cases of African swine fever have yet been reported in Germany, although some have been reported in the neighbouring countries.

A map showing the border between Denmark and Germany, where the wall is being built

German news agency dpa reported that Jan Philipp Albrecht, the Agriculture Minister of the German state of Schleswig-Holstein, said the disease is 'a serious threat for animals and the pig market.'

According to reports, however, he added: 'We have significant doubts about the usefulness and necessity of a fence between Denmark and Schleswig-Holstein.'

The European statistical agency Eurostat said there are some 150 million pigs in the EU and 40 percent of them are in Spain and Germany, with significant numbers also in France, Denmark, the Netherlands and Poland.

Denmark is the only EU country where pigs outnumber people, with 215 pigs to every 100 residents.

The 43.4-mile fence, pictured, is being built in an attempt to prevent the spread of African swine fever

US President Donald Trump made the idea of a solid wall between the American border with Mexico one of the key points during his presidential campaign in 2015.

'I would build a great wall, and nobody builds walls better than me, believe me, and I'll build them very inexpensively, I will build a great, great wall on our southern border,' he said.

'And I will have Mexico pay for that wall.'

Yesterday, Mr Trump tweeted: 'Build a wall and crime will fall!'