Royal Dutch Shell Plc said a ruptured North Sea pipeline continued to leak oil on Saturday and that it had been seeping crude into the sea for two days before the company declared it.
Shell said it was continuing to reduce pressure in the pipeline on Saturday, reducing the flow of oil.
Alex Salmond, leader of the Scottish regional government, told the BBC around 100 tonnes of oil, around 750 barrels, had leaked into the sea.
The Anglo Dutch oil major first revealed the leak late on Friday but a spokesman said on Saturday it had been detected two days earlier. A spokeswoman for the Maritime & Coastguard Agency said it had no information on the status of the clean up operation, and that none of its staff were at the spill site.
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Environmental group Greenpeace complained about the lack of information on the leak.
"Right now we don't know how serious this is, what we do know is that the North Sea is supposed to be ultra-safe, we're told spills can't happen there," oil campaigner Ben Ayliffe said in an e-mailed statement.