A British oil firm will announce on Wednesday that it has struck oil off Greenland, a find that could trigger a rush to exploit oil reserves in the pristine waters of the Arctic.
Cairn Energy, the first company to win permission to drill for oil in this sensitive environment, will break the news to the London stock market along with its half-yearly financial results.
The company declined to comment, but sources confirmed that hydrocarbons had been found, and Greenland's foreign office said it was hopeful Cairn would have something positive to reveal.
The news will delight the oil industry, which has long believed the Arctic harbours some of the last huge reserves.
It will also delight a Greenland government desperate to diversify its fragile economy away from a dependence on fishing, tourism and cash handouts from Denmark, which still formally has sovereignty over the world's largest island.
But the strike — the viability of which must still be assessed — will alarm Greenpeace and other activists who have been campaigning to stop drilling on the grounds that any accident would be disastrous.
Opposition has grown since the Deepwater Horizon blowout. On Tuesday the Greenpeace ship Esperanza was confronted by a Danish warship in the area. The Danish navy warned Greenpeace the ship would be boarded if it breaches a 500-metre exclusion zone around two wells drilled by Cairn.
The confrontation came as protesters targeted Cairn Energy's headquarters and six other businesses in Edinburgh to protest against the funding of oil and gas industries by the Royal Bank of Scotland.
The protests led to the shutting down of the RBS headquarters for the day. Twelve Climate Camp activists were arrested during the protest.
But the Arctic find will reinforce the reputation of Cairn in the oil industry. The firm has a strong track record of making discoveries in new frontiers.