Bangladesh has seen its exports of woven clothing slump since the end of an international textile trade deal on 31 December, reports say.
Bangladeshi jobs are at risk, campaigners warn
According to Agence France-Presse, exports of woven garments fell 21.34% in January from the previous year.
The 1974 Multi-Fibre Agreement (MFA) set up a quota system to govern the garment trade.
India and China are likely to benefit most from the end of the MFA by capitalising on economies of scale.
AFP quoted an un-named government official, who said January sales were $296.07m (£153.5m).
The garment industry is a key part of Bangladesh's economy, with many workers in the cities using their wages to support families in rural areas.
Textiles make up about 85% of Bangladesh's exports.
Almost half the country's 140 million people live on less than a dollar a day.
The MFA was originally intended to protect the garment trade of industrialised countries from poorer states with lower production costs.
Over time, however, it also acted to protect the clothing industry in those developing countries.
Campaigners said the slide in exports was likely to force hundreds of factories to close, and warned that replacement employment could prove hard to find.
"If these figures prove to be true, it's worse than we thought," said John McGhie of Christian Aid.
"It would be extremely bad news for Bangladesh."
Some of the decline, he said, could be the result of shifts in production over the latter half of last year as foreign buyers and firms prepared to look elsewhere for their garment imports rather than an abrupt one-month fall.
In December, Christian Aid published a report warning that as many as a million jobs could be lost in Bangladesh as a result of the end of the MFA.