Iran’s already fragile currency, the rial, has fallen in value by about 40 percent over the past week, battered by a combination of potent Western sanctions over the disputed Iranian nuclear program and new anxieties among Iranians about their government’s economic stewardship, analysts said.

While the value of the rial has eroded for the past few years as Iran’s economic isolation has deepened, the severity of the drop worsened with surprising speed in recent days as Iranians rushed to sell rials for dollars. By the end of the day on Monday, it cost about 34,800 rials to buy $1 in Tehran. The rate had been 24,600 rials as of last Monday.

“It’s sort of in a full-blown stampede mode today,” said Cliff Kupchan, a Washington-based analyst at the Eurasia Group, a political risk consulting firm. “There’s very little confidence among many Iranians in the government’s ability to adroitly manage economic policy.”

In another ominous sign, 10,000 Iranian workers signed a petition addressed to Iran’s labor minister complaining about the declines in their purchasing power and other economic maladies, suggesting that the accumulated impact of sanctions is putting more political pressure on the Iranian leadership, The Associated Press reported. President Mahmoud Ahmadinejad has said the sanctions, which are designed to force concessions on Iran’s nuclear program, would fail.