Ilford has blamed a double-digit increase in the price of b&w photographic papers and film on an ?unprecedented? rise in the cost of silver.

Ilford Monochrome Paper prices have this month risen by up to 20% while the price of a roll of 35mm film has shot up 12%.

A spokesman for Ilford?s brand owner, Harman technology Ltd, said: ?Our concerns started in early September when silver rose $20 per troy ounce and we have since been monitoring its rise hoping that the effect was temporary and that a drop would follow.?

He added: ?During the past 14 weeks we have been purchasing silver at ever-increasing rates and with great reluctance feel we can no longer delay a much needed price increase.

?To put this in perspective, silver is the largest single cost in our products and the recent rises have had a negative impact, running into millions of pounds per annum in our costs.?

Prices of other raw materials, such as paper base, have also gone up, according to Harman.

The firm has also pushed up the price of its Kentmere-branded paper and film.