The new Queensferry Crossing will not open until mid-May 2017, the infrastructure secretary has admitted.

In a written reply to a question by Scottish Conservative finance spokesperson Murdo Fraser, Keith Brown said the new bridge will not "achieve the target opening date of December 2016".

The delay has been caused due to "adverse weather" over April and May with 25 working days lost.

Brown said: "The contractor, Forth Crossing Bridge Constructors, has advised Transport Scotland that due to adverse weather conditions in April and May 2016 exceeding expectations and resulting in an increase in days lost to weather, they are unable to achieve the target opening date of December 2016 - which is six months ahead of the contractual completion date.

"The contractors remain on schedule to complete the project ahead of the contractual completion date. The contractors have taken additional steps to mitigate on-going weather impacts and have provided a revised timetable for completion to Transport Scotland and Scottish ministers".

The Queensferry Crossing is expected to widely replace the Forth Road Bridge as the main vehicle artery between Fife and the Lothians.

Fraser called the delay "very disappointing".

He 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.

"We saw the sheer disruption caused to people and businesses when the existing Forth Road Bridge was closed over Christmas.

"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."

In a statement to the Scottish Parliament Brown that a total of 25 working days had been lost to adverse weather conditions: 13 days in April and 12 in May.

The 1.7 mile long bridge will cost an estimated £1.35bn to complete. Brown insisted to MSPs the delay will not mean the cost of the project rising.

To deal with the setback the contractors have hired 100 additional workers.