The worst winter in years caused £4 million of damage to Birmingham roads.

Council officials are being forced to divert money from routine highways maintenance projects in order to carry out emergency repairs to potholes and cracked surfaces resulting from weeks of freezing temperatures during January and February.

Acting chief highway engineer Paul O’Day described the state of some roads as “critical”.

He said up to a third of surface material had been lost in a matter of weeks.

Mr O’Day added: “The long periods of freezing weather have caused a continuous cycle that has put deteriorated road surfaces under extreme stress.

“Surface courses have been destroyed by water penetrating minute cracks and joints and by the action of repeated swelling due to ice formation followed by shrinkage.

“Already over 30 roads have been found to be in this critical condition, presenting not only potholes but skidding hazards from the loose material.”

Mr O’Day is urging drivers to take extra care on damaged roads and report any hazards to the council.

The bitterly cold conditions damaged pavements and footways and contributed to a sharp increase in the total highways maintenance backlog, which now stands at £60 million.

The council expects the backlog to be wiped out if the Government approves a £2.2 billion Highways PFI, which would hand responsibility for maintaining the city’s entire road network to a private consortium.