M4 relief road cost transparency call by Conservatives
Support for an M4 relief road around Newport could increase if the first minister was more transparent on the cost, the Welsh Tories have said.
Their leader Andrew RT Davies asked Carwyn Jones to explain why he told BBC Radio Wales he thought it would cost "way below" the official £1bn estimate.
The first minister said he did not want to show his cards ahead of negotiations with potential contractors.
A previous plan was dropped in 2009 when £1bn was judged unaffordable.
However, the project was revived and, according to Welsh government website details last updated in July, is still predicted to cost around £1bn.
Pressed on the issue during First Minister's Questions on Tuesday, Mr Jones refused to announce any new estimate.
"That is the equivalent of showing your cards in a poker game because we will have companies tendering for contracts to build the M4 if it gets to that stage, as is our plan," he said.
"Revealing beforehand what your target figure is is not a wise move in the world of business."
Mr Davies responded, saying: "It is not unreasonable to ask for clarity around these figures and around these numbers when so much effort and civil service time is put into it.
"Ultimately you could get more support for the project if you were more transparent in the remarks that were made."
None of the opposition parties at the assembly have supported the Welsh government's plan to build a new six lane motorway to the south of Newport.
The Conservatives have said there should be a review of the plan, while Plaid Cymru and the Liberal Democrats support a proposal to upgrade the existing southern distributor road through Newport.
Outside the chamber, Mr Davies told BBC Wales the Tories would consider supporting a new motorway if the cost is reduced.
A final decision is expected after the assembly election in May and, subject to approval and a public inquiry, the road could be completed in 2021.