It was a shocking spectacle and one Oxford shoppers never thought they would see again - broken paving slabs in Cornmarket Street.

German artist Ursula Ziegler brought back painful memories yesterday when she decided to push nine paving slabs the length of the city centre thoroughfare - all in the name of art.

She left pensioners tripping in her wake and scratched the biscuit-coloured asphalt surface.

The project to resurface the street cost Oxford city and county councils about £5m - double the original estimate, after contractors discovered underground cellars. Work was finally completed last June after years of disruption.

Miss Ziegler, a 36-year-old artist, who is on a placement at Oxford University's Ruskin School of Fine Art, said she contacted the councils for permission to carry out the live artwork, but they did not respond, so she decided to go ahead anyway.

She said: "Some shoppers have been tripping up on the paving stones and I'm really sorry, but I didn't mean to hurt anyone.

"I won't be clearing up unless the council forces me to."

After the Oxford Mail alerted independent city councillor Paul Sargent, he warned Ms Ziegler she could be fined for damaging the road surface, and told her he would be contacting the police unless she removed her artwork.

The councillor for Carfax said: "I love contemporary art but I am mortified by this. It is destructive and potentially dangerous. We spent a fortune resurfacing this street and this is the last thing we need."

Entitled Time Tip, Ms Ziegler used nine paving slabs, which were once outside the Radcliffe Camera until resurfacing work took place.

She also used 50kg of sand, which she poured through holes in the limestone slabs as she progressed slowly down the street from Carfax.

She described her work as "a contemplation of time passing, and of my time here in Oxford in relation to all time unfolding".

Ms Ziegler started her journey at 10am and abandoned her work shortly after 2pm, after she was confronted by Mr Sargent. She then removed the stones, but left the sand.

There was a mixed reaction.

Gary Butchart, 29, of The Slade, Headington, described it as "interesting and quite thought provoking" but others were angered. Jennifer Webb, from Headington, said: "We paid far too much out of council tax to have this street resurfaced, and now this woman has messed it up."

Ms Ziegler admitted: "I knew nothing about the history of Cornmarket until someone told me about it this morning. I wanted a street with an obvious start and finishing point for this."

David Robertson, the county council's cabinet member for transport, who dealt with the completion of the costly resurfacing scheme, said: "I'm gobsmacked by this and it makes me wonder what planet these people come from.

"I've sent our engineers out to check if there has been any serious damage."