MEXICO CITY—The Bank of Mexico says the amount of money sent home by Mexicans working abroad plunged 20 percent in September. That was the biggest drop since October 2009, when migrants were struggling to find jobs amid the worldwide economic crisis.

Mexico's central bank said Thursday that remittances in September fell to $1.66 billion from the $1.88 billion sent home from abroad during the same month in 2011.

The biggest drop in remittances was registered in October 2009 when they fell nearly 36 percent.

Nearly all remittances to Mexico come from the United States, where an estimated 12 million Mexican citizens live.

Experts blame the drop on the decrease in construction and manufacturing jobs in the U.S. in the past months, which may be attracting fewer workers.