New Queensferry Crossing opening delayed until May 2017
The new £1.35bn road bridge across the Forth will now open in May 2017, six months later than originally planned.
The Queensferry Crossing was scheduled to be completed by December this year but that deadline will not be met.
Keith Brown, the cabinet secretary for the economy, said the delay had been caused by "adverse weather conditions" in April and May.
In a statement to MSPs he said the delay was a "very recent development" caused by high winds earlier this year.
Mr Brown said the contractor, Forth Crossing Bridge Constructors (FCBC), had advised Transport Scotland that it was unable to achieve a target opening date of December 2016.
In response to a question from Mid Scotland and Fife MSP Murdo Fraser, the minister said the bad weather "exceeded expectations" and resulted in an increase in the number of days lost to the weather.
He told MSPs that 25 days were lost over April and May due to high winds, using up the time contractors had put aside for contingencies.
Work was also halted in April when a 60-year-old worker was killed on the site.
Mr Brown said contractors remain on schedule to complete the project ahead of the contractual completion date - six months after the December target.
He also insisted that there would be no financial impact or cost to the taxpayer due to the opening date being pushed back, but did admit that "weather is still a factor" in the May 2017 target.
The Scottish Conservatives said ministers must now give a date for completion.
Murdo Fraser said: "This is very disappointing news for people on both sides of the bridge.
"They were continually told by the Scottish government that this project was ahead of schedule and would soon be up and running.
"Now we find this is not the case, so the SNP must now give an exact date when this will be completed by."
The existing Forth Road Bridge was closed to traffic for almost three weeks in December after a crack was discovered under a truss in the roadway.
Mr Fraser called for assurances that the current bridge is fit to carry on while the new crossing is completed.
"We saw the sheer disruption caused to people and businesses when the existing Forth Road Bridge was closed over Christmas," he said.
"It's essential we know whether or not the patch-and-mend approach taken at that point will be enough to ensure it can cope until the Queensferry Crossing opens."
Mr Brown insisted that the existing Forth Road Bridge could handle an extra six months of heavy traffic.
Labour's Alex Rowley said the delay "will be greeted with great disappointment in Fife and beyond".
Stressing that the building of the new bridge remains good news, he said it was "important that ministers do not announce unrealistic deadlines", calling for "full transparency" in the project.
Lib Dem MSP Alex Cole-Hamiltion, whose Edinburgh Western ward includes the southern end of the bridge, said the project was in "abject distress".
He queried "how on earth" 25 days of delays had caused the opening date to be pushed back 180 days.
Mr Brown said "everything possible" was being done to get the bridge open as quickly as possible, in line with safety guidelines.
In February, Transport Scotland said the project was scheduled to finish "on time and under budget".
But earlier this week, in the wake of newspaper reports that the opening of the bridge could be delayed, the transport agency would not give a completion date.
Instead, it said FCBC was "making every effort to open the bridge as soon as possible".