The Queensferry Crossing will not now open in May, economy secretary Keith Brown has admitted to MSPs
Completion of the £1.35 billion replacement for the Forth Road Bridge has been put back by "adverse weather conditions".
However, Mr Brown would not be drawn on reports that contractors had asked for the completion date to be extended to September.
The news follows the opening being delayed from last December because of strong winds hampering progress.
When announcing that original delay last June, Mr Brown assured MSPs that the the Forth Crossing Building Constructors (FCBC) had "built in allowances for future weather based on the experience to date".
He also said that FCBC "fully expects the project to be complete well within the timeframe of its contract", which ends in June.
He said then: "Although we will not meet the December opening target, it remains true that the project will be completed by the contractual completion date."
One senior construction source told The Scotsman: "This is not surprising but it is egg on their face".
Mr Brown is due to provide further details to Holyrood's rural economy and connectivity (REC) committee at 9:30am tomorrow.
He will consider overnight a report from officials following an update from FCBC to the Scottish Government's Transport Scotland agency, which is in charge of the project.
The minister was responding to a question from Mid Scotland and Fife Conservative MSP Murdo Fraser.
He told MSPs: "Following my recent appearance at the REC committee on 8 March, I asked FCBC, the contractor, to carry out a thorough review of their programme through to project completion.
"That work has indicated that adverse weather conditions, particularly wind, has had an impact on the removal of the construction cranes and, therefore, on the estimated completion date.
"Transport Scotland is currently assessing that review carried out by FCBC and I expect to receive a report from them this evening.
"I've agreed to provide a detailed update to the committee tomorrow morning.
"This bridge will be there for 120 years, it's very important that we both get it right and that we do it safely."
Mr Brown said it had taken 65 days to take down cranes that would normally take 15 days, because of consistently high winds.
Mr Fraser later tweeted: "New Queensferry Crossing was promised by FM [First Minister] for end 2016. Then end May 2017. Now delayed again. Very disappointing for constituents."
Confirmation of the delay comes days after speculation increased that the project was again running behind schedule.
Transport Scotland said it was difficult to give a "cast iron guarantee" that the bridge would be finished on schedule after sources said the timetable was getting "extremely tight".
On Sunday, its spokesman was reported as saying the contractors were "making every effort to open this iconic structure at the earliest opportunity" and "the target date for opening to traffic remains the end of May."
"For example, it has taken 65 days to actually take down one of the cranes which would normally have taken 15 days because of the consistently high winds.