First Minister Alex Salmond said sufficient supplies could be imported after the Grangemouth petrochemical plant and oil refinery closed yesterday over a bitter dispute.
Ineos said the facility was "shut and will remain shut" into next week following the breakdown of talks with the union Unite.
On the issue of petrol supplies, Mr Salmond said: "People should not be concerned about that. The contingency plans are very strong indeed".
Mr Salmond said the immediate threat to fuel supplies in Scotland was lower than during a previous strike in 2008.
It came after a 48-hour strike for the Stirlingshire site, which had been due to begin at 7am on Sunday, was called off. The action had threatened disruption to petrol supplies throughout Scotland and northern England.
It is understood it will take around three weeks for the plant to return to full operation once any decision to reopen is made.
Scottish Secretary Alistair Carmichael said the decision to keep the site closed was a disappointing setback, adding: "Be in no doubt that the stakes are exceptionally high here."
Long-term closure of the complex, which processes up to 210,000 barrels of oil per day and processes around 80% of Scotland's fuel, would have a serious effect on the Scottish economy.
The site has 2500 staff and contractors and supports thousands more jobs indirectly in the surrounding area.
Ineos has assured ministers a pipeline to BP's Kinneil terminal, which processes oil from the Forties field in the North Sea would stay open. Stocks lost during the dispute would also be replenished.
However, Mr Salmond added: "There's still now huge uncertainty about the long-term future of what is a major chemical and industrial complex."
Ineos said it would put a new proposal to the union today to which it expected a response by Monday. The company, which refused to elaborate on the nature of the proposal, would "review its position" with its shareholders on Tuesday.
Mr Salmond said the Scottish Government would do all it could to help, but added it was for the management and unions to reach agreement.
In a statement, Ineos said: "Grangemouth is financially distressed. The industrial action called by Unite has inflicted significant further damage on the company. Ineos will put a proposal to the workforce and expects a response on Monday. The company will review its position with its shareholders on Tuesday."
Unite, which accused the company of economic vandalism, claimed it had cancelled the strike to protect the facility from its owner's "scandalous behaviour". Ineos representatives had "walked away" after a marathon 16-hour session of talks at the Acas conciliation service in Glasgow that concluded at 5am yesterday, officials said.
Ineos had started to shut down the plant in advance of the strike called by the union to defend convener Stephen Deans, who is being investigated by the company for union activities in breach of company rules.
A spokeswoman for Ineos, which has previously warned Grangemouth is losing £10 million a month and will close in 2017 without investment and cost-cutting, said: "Grangemouth is now closed down and will remain closed down until Tuesday."
Pat Rafferty, Unite's Scottish secretary, said: "Ineos's decision to keep Grangemouth shut is an act of economic vandalism. There is no reason for the site to remain shut - the company is holding Scotland to ransom.
"The Scottish and Westminster governments must act without delay. Unite acted in the national interest by calling off the strike as Ineos had no right to initiate a cold shutdown - a shutdown against the wishes of the Health and Safety Executive, and against the economic interests of the country.
Michael Connarty, Labour MP for Linlithgow and East Falkirk, claimed the firm engineered the dispute to create a climate in which loss-making parts of the plant could be closed. He said: "This is about downsizing the plant. They have already said that, without investment, parts would have to close in 2017. Instead of negotiating this they are using this dispute to achieve this, while at the same time blaming the workforce."