Ferrovial said the “fair value” of Amey in the UK now is £88m.
Amey has been up for sale since late last year when Ferrovial decided to look at offloading its services division.
Ferrovial said: “Amey’s value has been affected by the situation of the UK services sector in recent years, due to numerous uncertainties attributable to budget cuts by local administrations, among other factors.
“Moreover, contractual disputes have proliferated between service providers and their clients.”
Amey is embroiled in a major row with Birmingham City Council over its £2.7bn highways maintenance contract.
Ferrovial said: “Amey has a PFI agreement signed in 2010 with Birmingham City Council, which retained all related payments in 2018.
“The UK subsidiary, and the other stakeholders involved in the contract, are negotiating with the Council to attain a solution that is satisfactory to all parties.”