A runaway weather balloon which has been tracked by the air forces of three countries is believed to have come down in the Arctic Sea, the company that launched it said yesterday.
Aircraft from Canada, Britain and the US had monitored the giant balloon's progress across the Atlantic, with air traffic controllers diverting planes from its path.
Last Thursday Canadian jet fighters fired more than 1,000 rounds at the balloon, but failed to bring it down.
Mr Dale Sommerseldt, vicepresident of Scientific Instrumentation Ltd, told BBC Radio yesterday the balloon had last been seen west of Spitsbergen, which straddles the Arctic Circle north of the Norwegian mainland.
He said: "It's no longer a threat to Arctic and transatlantic flights, which is a big relief for us today.
"As there were no reports from aircraft in the area today we believe it's finally down, in the sea, or possibly on pack ice."
The unmanned 330-ft tall balloon was launched last Monday from Vanscoy, Saskatoon, to measure ozone levels over Canada. It was supposed to have come back down on Wednesday.
Despite its size - it was as tall as a 25-storey building and had a surface area which would cover five football fields if stretched out - two Canadian CF-18 fighter pilots failed to bring it down over Newfoundland.
A Canadian military spokesman, Lieut Steve Willis, said hitting a comparatively stationary target from supersonic speed was not easy.