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The parliamentary committees for Petitions and for Women and Equalities responded to a petition to make it illegal to force women to wear high heels at work.
The petition, which got more than 152,000 signatures, was filed by receptionist Nicola Thorp, who was sent home from work last year for not wearing high heels.
"The government has said that the dress code imposed on Nicola Thorp was unlawful-but the Committees heard that requirements for women to wear high heels at work remain widespread," the committees said in a joint response.
The MPs said that "the Equality Act 2010 is not yet fully effective in protecting workers from discrimination."
Helen Jones, chair of the Petitions Committee, said: "It's not enough for the law to be clear in principle-it must also work in practice. The government has said that the way that Nicola Thorp was treated by her employer is against the law, but that didn't stop her being sent home from work without pay."
The government should "introduce awareness and guidance campaigns" for firms to make sure they understand the law and increase financial penalties for those that breach it, the committees said.
Thorp's former employer, Portico, told BBC News: "We fully support the recommendations within the report and welcome the debate in Parliament in March. When this issue was raised last year we immediately updated our uniform guidance."