"Apparently no one knows what there is in the 54 dumpsites at Thule Air Base that are a time bomb for Greenland," Mads Christensen, a Greenpeace activist in Copenhagen, told AFP.

Greenpeace, which obtained a copy of the 4,000-page US document, rapped the Danish government for putting pressure on the semi-autonomous Greenlanders to approve US plans for a controversial missile defence shield, which would entail modernising a US radar station in Thule in the northwest of the Arctic island.

"It is shameful that the Danish government is pushing Greenlanders to say Yes to a new deal with the United States on the modernisation of Thule... when nobody knows the extent of waste problem and who will pay for damage to the ultra-sensitive artic region," he said.

In a confidential internal document made available to Greenpeace, the Danish environment ministry was highly critical of the US report, saying it "uses risk criteria that are far removed from international standards."

The ministry document also said it conducted its own investigation, in 2001, in the Inuit village of Dundas (Uummannaq in Inuit), which remained under US administration from 1953 until last February.

At least one sample from Dundas showed higher than authorised levels of PCB (polychlorobiphnyles) chemicals, the document said.

"There are more than 50 other dumpsites at the Thule base. What will happen when the United States leaves, since according to the 1951 US-Danish defence treaty on Thule Air Base, they do not have to clean up before leaving?" said Christensen.

The group criticised Copenhagen for keeping the US report under wraps, saying it would send a copy to the Inuit Circumpolar Conference, a non-governmental organisation that represents 125,000 Inuit in Greenland, Russia, Alaska and Canada.

"We can also send it to the local Greenland government is they wish us to," Christensen said.

Danish foreign minister Per Stig Moeller was due to visit Greenland on Tuesday to sign an agreement giving local authorities equal rights with Copenhagen in Greenland-related foreign policy matters.

This is a condition set by the local Greenland government in exchange for accepting the modernisation of Thule base.

Greenland's 57,000 residents generally oppose the US plan because they fear it will put their island at the centre of a new conflict.

The United States has formally asked Denmark to allow a technical upgrading of the Cold War-era Thule base, thought to be one of the major listening posts required for the National Missile Defense (NMD) shield to be operational.

The Danish government is expected to announce its formal decision at the end of April or early May, according to government officials, but it is known to be favourable to the US plan.

SPACE.WIRE