Western economic sanctions imposed on Iran over its disputed nuclear program have severely depressed the value of its national currency, the rial, causing higher inflation and forcing Iranians to carry ever-fatter wads of bank notes to buy everyday items. But the sanctions have also presented a new complication to Iran’s banking authorities: they may not be able to print enough money.

At least three European companies that have been providing currency production services to Iran say they have stopped doing business there. One of the companies, Koenig & Bauer AG of Würzburg, Germany, also says it has not responded to an Iranian request for bids to make presses to print new rials.

Koenig & Bauer’s disclosure was contained in a mailed response to a query by United Against Nuclear Iran, a New York-based sanctions advocacy group, which seized upon the 40 percent drop in the rial’s value this month to begin a campaign aimed at the currency itself.

The group began by pressing the Europe-based bank note industry, which has historically counted Iran as a client, to further ostracize the country by denying its central bank the basics of a functioning currency system: the printing presses, engraving paper, anticounterfeiting technology and other services needed to provide enough rials.