His reaction stood in stark contrast to that of Progress Party leader Siv Jensen, who immediately called for tighter restrictions on immigration when Statistics Norway published its projections on Tuesday.

“No, I’m not concerned,” Stang told news agency NTB.  

“But the high number shows that we’ll have a major task integrating immigrants. It’s up to parliament and the government to decide how many people will move to the country. Our job is to integrate them.”

The mayor pointed out that 2040 remains a distant point in time: by then, many immigrants will have lived in Norway for almost 100 years.

“It’s an interesting question as to how long one should be considered an immigrant. For me, the most important thing is to be able to provide all immigrants with the best possible schools so they can receive a good education and get a job. It’s then of lesser importance what skin colour, religion or sexual orientation one has,” said Stand.

In 2040, 70 percent of the Norwegian capital’s first and second generation immigrants will have their roots in countries outside the 30-member European Economic Area, Statistics Norway said.

The study, the first ever projection of immigration trends to be published in Norway, shows that the largest cities will also see the biggest upsurge in immigrant numbers.  

Immigrants are defined in the statistics as either people who have either moved to Norway from another country, or the Norway-born children of two first-generation immigrants.

According to Statistics Norway’s most likely scenario, Oslo’s immigrant population will rise from today’s 28 percent to 47 percent in 2040.

In the country as a whole, the immigrant population is expected to jump from 12 to 24 percent, or from 600,000 people today to 1.5 million in 2040.

Centre Party Secretary of State Dag-Henrik Sandbakken, at the Ministry of Local Government and Regional Development, noted that rising immigration is part of a global trend that will continue to present Norway with a mixture of possibilities and challenges.

“Norway has benefited from the high level of workforce immigration to the country in recent years. Statistics Norway’s prognosis makes for exciting reading, even if it also entails many uncertainties,” Sandbakken told NTB.

Local governments all over the country have become more accustomed to immigration and are well prepared to meet new integration challenges head on, said Sandbakken.  

But for Siv Jensen, the trend is deeply worrying.

“For far too long Norway has been an attractive country for asylum seekers and immigrants. The Progress Party believes it’s high time for more restrictive policies,” she said on Tuesday.

“The more immigrants there are the more difficult it will be to make integration work,” according to the 42-year-old head of the populist opposition party, which has long called for stricter immigration rules.

Jensen said the Progress Party wanted Norway to hand out fewer residence permits to immigrants. She also called for the country to tighten immigration policy loopholes.

For instance, she suggested that an immigrant marrying somebody from the same country of origin in Norway should not automatically be granted residency.

“We must admit that there are major differences in the types of integration challenges posed by different immigrants.

"Norway still has a major need for workers, and labour-market immigration from Eastern Europe presents completely different integration challenges than immigration from Eastern Africa,” said Jensen.