The revelation comes a day after latest police figures revealed metal thefts in the county had more than quadrupled in the last year, to an average of almost three a day.

A manhole cover has been stolen in the last few days from the pavement outside the Thomas A Becket pub, St James Road, St James, Northampton, creating a danger to passers-by.

A woman, who came across the hole and placed a white board over it, said: "It's dangerous because a kid or a little dog could fall down the hole.

"It is also going to be a real hazard for elderly people and the blind."

Another manhole cover was taken two weeks ago from the pathway next to the River Nene in Footmeadow Park.

Police have revealed car parts are also being targeted by metal thieves, along with the common targets of lead from roofs.

Catalytic converters are estimated to hold between 1g and 3g of platinum. The precious metal is part of the "scrubbing process", which cleans up fuel emissions from vehicles. It is thought that the stolen converters can be sold for at least £120 each.

A spokesman for Northamptonshire Police said: "We had a few incidents of catalytic converter thefts at the beginning of the year in the Corby area, Towcester and the Riverside Business Park, in Northampton.

"It is not a major issue in the county. However, we are aware that it's a problem in other parts of the country. We share intelligence with other forces.

"As part of the metal problem, things like drain covers have been taken; it is not just lead from church roofs."

In the 12 months up to the start of April there was a total of 988 metal thefts across the county – fuelled by the soaring price of scrap metal – compared with a total of 222 for 2006/07.

The largest number was in Northampton where there were 410 metal thefts compared with 95 in the previous 12 months.