About 20 percent of those jailed in Dubai are held on bounced cheque charges and most of the detained are foreign workers, the UK's Times newspaper has reported.
Citing Dubai police, the Times said the problem of bounced cheques is far more widespread in the UAE than officially reported.
Official figures for the first third of 2009 reveal 544,196 cheques bounced in the UAE, around 5.7 percent of all cheques issued, according to the newspaper.
But analysts claim the figure is as high as 25 percent when all private sector cheques are counted in the process, the newspaper said without elaborating.
Some British expats, struggling in the world economic downturn, are among the imprisoned, the Times said.
"Sadly many have ended up writing bounced cheques, having their passports confiscated so they cannot leave the country," said Ghanem Nuseibeh, a senior analyst at consultancy firm Political Capita, told the newspaper.
The cheque-writing system in the UAE is complicated because it also serves as a credit card system to make it easier for foreigners to do business in the emirates.
UAE authorities have vowed to crackdown on financial lawbreakers.