How much is a one rupee coin worth? Up to 2500 rupees if you believe the rumours sweeping Pakistan that the humble coin had inadvertently been made with gold instead of the usual tiny percentage of copper.

Shopkeepers across the country have reported being approached by dealers offering vast sums for a coin – with a face value of less than one pence – that inflation has made so worthless as to be frequently tossed aside.

Such is the excitement that the central bank has been forced to issue a denial to calm the hysteria and prevent speculators losing their savings.

Arshad, an ice cream seller in Islamabad, said children had been asking him for his loose change.

"I didn't understand what was happening at first," he said. "Then after a while I had parents coming out and asking to buy the coins and I read what was happening in the papers.

"No one has offered me as much as 1000 rupees but we have all heard it is happening."

One newspaper claimed a beggar had sold 150 of the coins and bought a motorbike with the proceeds.

Other rumours suggested the coins contained uranium and were being smuggled across the border for Iran's secret atomic weapons programme.

A spokesman for the State Bank of Pakistan described the rumours as a "racket".

Syed Wasimuddin said the coins were made from aluminium and copper rather than gold, and advised members of the public not buy or sell them for any price other than their face value.