Greenlanders have welcomed reports that the US wants to invest in their island, but said the money had to come without conditions.

The US administration is expected to announce the opening of an Agency for International Development office at the new US consulate in the capital, Nuuk, and at least $12m (£9.7m) in aid projects.

The announcement, expected on Thursday in Washington, will come less than a year after President Donald Trump drew derision for expressing an interest in buying Greenland, a semi-autonomous Danish territory. But suggestions of a greater US presence in Greenland were met with criticism in Greenland and Denmark on Thursday.

Aaja Chemnitz Larsen from the left-leaning opposition party Inuit Ataqatigiit described it as a charm offensive.

“The Americans are welcome if they want to invest in Greenland,” she said. “But it is important to make sure that Greenland doesn’t owe anything back to the United States. We are sceptical about what they really want besides influence.”

She added that it must clear what the money should be spent on.

Jon Rahbek-Clemmensen, an associate professor with the Royal Danish Defence College in Copenhagen, said the US had been missing out in terms of its Arctic strategy, giving Russia and China a head start in the region, and was now coming back with a large sum of money. They are trying to get back to having a presence in the Arctic and are doing it “with a big fanfare”, he said.

An opinion piece written earlier this week by the American ambassador to Denmark, Carla Sands, previewed the announcement and said the US would be the preferred partner in the Arctic, a comment that sparked harsh reactions in Denmark.

“They have clearly crossed the line,” said Carsten Hønge, an outspoken member of the left-leaning Socialist People’s party that supports the Social Democrat-led minority government. “We must draw a line in the ice cap.”

Søren Espersen of the opposition Danish People’s party told the Danish broadcaster DR that financial aid was something you say about developing countries. “But Greenland is not a developing country. It is a western democracy. I think its reprehensible.”

Greenland covers 2.166m sq km (836,000 sq miles) but has a population of only 56,000, mainly Inuit.

Q&A Why might Donald Trump want to buy Greenland? Show Greenland harbours some of the largest deposits of rare-earth metals, including neodymium, praseodymium, dysprosium and terbium, along with uranium and the byproducts of zinc. US corporations once thought of China as a benign supplier of rare-earth metals for mobile phones, computers and more recently electric cars. And the US government was relaxed when Chinese companies began hoovering up mines across central and southern Africa to secure an even greater dominance of the global market.

But the arrival of Xi Jinping as China’s leader, and his more aggressive foreign policy stance, has spooked many US policymakers. Among Trump’s advisers, the need for greater economic independence has raced up the agenda. A potential target for the US is Greenland Minerals, an Australian company that has generated a good deal of excitement since it started operating on Greenland’s south-west peninsula in 2007 to develop the Kvanefjeld mine, which is home to many rare-earth metals. More than 100m tonnes of ore are believed to be sitting below the surface and the project is expected to become one of the largest global producers outside China. Phillip Inman

Last August, Trump’s desire to buy Greenland emerged in press reports in Washington. The Inuit premier, Kim Kielsen, said at the time the island was not for sale, while the Danish prime minister, Mette Frederiksen, said: “Greenland is not Danish. Greenland is Greenlandic. I persistently hope that this is not something that is seriously meant.”

Retreating ice could uncover potential oil and mineral resources in Greenland which, if successfully tapped, could dramatically change the island’s fortunes. But no oil has yet been found in Greenlandic waters and 80% of the island is covered by an ice sheet that is up to 2 miles (3km) thick, which means exploration is only possible in coastal regions.

Even there, conditions are far from ideal, due to the long winter with frozen ports, 24-hour darkness and temperatures regularly dropping below -30C (-22F) in northern parts.