A public consultation has been launched to examine controversial proposals to transfer large quantities of oil between ships in the Firth of Forth.
Ship to ship oil transfers already take place at Scapa Flow in Orkney
Forth Ports is in favour of the plan to transfer Russian oil to tankers, four miles off the Fife coast, at rates of up to 3,000 tonnes per hour.
But Fife Council believes it could pose a major hazard.
UK Transport Secretary Alistair Darling said the consultation would assess the implications for nature conservation.
Mr Darling pointed out that such transfers already take place at Scapa Flow in Orkney, Sullom Voe in Shetland and at the Nigg oil terminal in the Cromarty Firth.
They are lawful and do not need approval by the transport secretary.
However, the harbour authority must get his go-ahead for its oil spill contingency plans.
It is understood Mr Darling believes the consultation has been inadequate so far and will ask for views on the contingency plans.
Sunderland company Melbourne Marine Services (MMS) wants to carry out the transfers in the Forth about four miles off Methil.
The oil would be switched to vessels bound for China or eastern Europe.
Fife Council has described the proposal as one of the most serious threats ever faced by the area.
Green Mid-Scotland and Fife MSP Mark Ruskell branded the consultation a smokescreen, claiming the "ludicrous" oil transfer plan would threaten the economy and environment around the Forth.
He said: "This consultation assumes that ship-to-ship oil transfer will go ahead in the Firth of Forth. It's about consulting on a plan to deal with an oil spill, not about questioning whether this proposal should go ahead in the first place.
"European law dictates that we must put the protection of the sensitive habitats in the Forth at the forefront, not work out how we can clean them up once they are polluted."