Transport Secretary Michael Matheson has told MSPs that there is no definitive date for the opening of the new Aberdeen bypass.
The £745m 28-mile (45km) bypass was approved by Scottish ministers in 2009 but faced legal action.
It was due to open in the spring but was put back to autumn. However there have been delays with the construction of the bridge over the River Don.
Mr Matheson said it would open when safe.
He was providing an update on the timescales for the project.
MSPs were also told that Transport Scotland is calling on the contractors to agree a variation to their contract, which would allow the Stonehaven to Craibstone section of the road to open.
Mr Matheson said contractors were often "ambitious with their targets" and the bypass opening would be delivered at "earliest opportunity".
He said a definitive opening date would be supplied as soon as possible - with safety paramount.
He said: "I am fully aware of the eagerness of the people of the north east of Scotland waiting for their new road".
Mr Matheson said it was time for the contractor to "stop deliberating and start acting".
He said: "The contractor is working hard to repair the (River Don) defects and earlier this week it reported it was targeting a December opening date.
"However, it is not possible to provide a definitive date as there are a number of factors which could influence it including technical issues and other physical factors such as weather.
"We will continue to work closely with the AWPR contractor to ensure everything that can reasonably be done, is being done, and we will provide a definitive date for the opening of this section as soon as possible."
He has called for an urgent meeting with the contractor board members to seek clarity on the timescales for opening the remaining sections of the bypass.
Conservative MSP Liam Kerr described the situation as a "disgrace".
Labour MSP Colin Smyth said it was not good enough the transport secretary could not give a firm date for the opening of the bypass.
The transport secretary stressed the offer of a variation in the contract had been with the contractors for some time and he hoped they would take it on as quickly as possible.
Paul Haldane, director of Stonehaven-based taxi firm Dash Cabs, expressed frustration at the ongoing delays.
He told BBC Scotland the firm could not expand until the quicker bypass routes were available.
He described the situation as "nothing short of incredible".
The first main bypass part - between Parkhill and Blackdog - opened in June.
And the Balmedie to Tipperty section of the bypass fully opened to traffic in August.
The ongoing work is one of the biggest infrastructure projects in Scotland.
Preparatory work on the Aberdeen bypass began in August 2014, and construction work began in February 2015.