US lawmakers on Thursday urged a quick review of the duty-free access granted to many products from Bangladesh, voicing alarm over labor conditions after a factory fire killed 111 workers.

The 12 Democratic lawmakers, many of whom serve on the tax-writing House Ways and Means Committee, said that Bangladesh appeared to be "going in the opposite direction" despite promises of labor reforms.

"We are seriously concerned about the deterioration of working conditions and worker rights in Bangladesh," said the letter to US Trade Representative Ron Kirk.

"The Tazreen fire is yet another wake-up call that these kinds of concerns must be vigorously addressed," it said.

Signatories included Representative Joe Crowley, founder of a congressional caucus on Bangladesh, and Representative Sandy Levin, the ranking member of President Barack Obama's Democratic Party on the Ways and Means Committee.

A fire on the night of November 24 tore through the Tazreen Fashion Factory -- which supplied clothes for retailers including Walmart -- killing the mostly female workers after supervisors initially prevented them from leaving.

The lawmakers asked the US Trade Representative's office to accelerate its review of whether Bangladesh should remain part of the Generalized System of Preferences, through which the United States offers duty-free access for up to 5,000 products from developing countries that meet labor standards.

The office has been assessing Bangladesh's eligibility after complaints about its record from the AFL-CIO, the largest US labor union confederation.

However, the Generalized System of Preferences does not offer duty-free access for textiles, which account for up to 80 percent of Bangladesh's exports.