The Scottish scientist asked to discover the cause of cracked paving in Oxford's Cornmarket Street is confident the problems can be solved.

Work was due to restart after Christmas but, after cracks appeared in the new granite stones, county council officers postponed the £2.2m project and called for an investigation.

Dr Derek Fordyce, from the department of civil and offshore engineering at Heriot-Watt University, Edinburgh, has been called in to give expert advice.

He visited Oxford before Christmas to examine the cracking, and chunks of the paving have been sent to Edinburgh for examination.

He added: "I have every confidence that this scheme can be completed but it would be unreasonable to give any timescale before I have completed my report."

Eddie Luck, the county council's assistant director of transport development, said contractors would be advised, after completion of Dr Fordyce's report.

He said: "We have always been confident that this is a technical problem which can be solved.

"There has never been any intention of doing anything other than getting Cornmarket put right and finished off."

The city council, which is paying £1.8m towards the cost of the project, said it cannot afford to pay any more if costs increase.

Dr Fordyce completed his Master's Degree on the weathering properties of petroleum bitumens, and his research interests lie in the performance of asphaltic pavement surfaces and emulsion Macadam mixtures. He was appointed lecturer at Heriot-Watt University in 1980 and senior lecturer in 1992.