Earlier today, Balfour Beatty said it was halting discussions between the two listed firms after Carillion said it was not interested in proceeding unless the Balfour-owned consultancy Parsons Brinckerhoff was included in the merger.
Wolverhampton-based Carillion has now released its own statement to the stock exchange in response, saying it continues to believe in the "powerful rationale" of combining the two companies.
Both firms specialise in large-scale construction and infrastructure projects, with Carillion leading the Library of Birmingham development while Balfour Beatty's projects include the Midland Metro extension in Birmingham city centre and the new Queen Elizabeth Hospital, in Selly Oak.
They announced last week they had entered merger discussions.
Carillion's statement said: "The board yesterday concluded, on the basis of analysis to date, that for the combination to satisfy (our) requirements....it would be essential to retain the stability and dependability of Parsons Brinckerhoff's earnings.
"The board is surprised by Balfour Beatty's reaction as the work to date has led to increased confidence in the potential to realise very material value for the benefit of both sets of shareholders.
"(We) continue to believe in the powerful strategic rationale of a combination and the capability of such a combination to create very significant shareholder value.
"The board will therefore give further consideration to its position in the light of its requirements that due diligence would have to be concluded to its satisfaction and the boards would have to recommend a combination to their shareholders."
Carillion said it would make a further announcement in due course and has until 5pm on August 21 to announce either a firm intention to make a deal or confirm it is pulling out.
As with Balfour Beatty's statement earlier today, Carillion's was made without the other party's consent.
This week on the free Birmingham Post app: First World War centenary special, interview with Hollywood star Vin Diesel and how Tolkien novel nearly went unpublished as well as daily breaking news. Download it here.