The head of a Mexican cultural affairs commission and wife of the country's president on Thursday accused US fashion brand Ralph Lauren of plagiarising Indigenous designs.

"Hey Ralph: we already realised that you really like Mexican designs," Beatriz Gutierrez wrote on social media.

"However, by copying these designs you're committing plagiarism, and as you know, plagiarism is illegal and immoral," added Gutierrez, who is married to President Andres Manuel Lopez Obrador.

She posted a picture of a Ralph Lauren labelled jacket whose design she said matched those of the Mexican communities of Contla and Saltillo.

"At least acknowledge it. And hopefully you will compensate the original communities that do this work with love and not for million-dollar profit," added Gutierrez, a journalist and writer.

Mexico regularly denounces what it calls plagiarism by foreign designers of the motifs, embroidery and colors of its Indigenous communities.

The Latin American nation has previously lodged complaints against major clothing brands including Zara, Mango and SHEIN.

It won an apology in 2020 from French designer Isabel Marant for the use of the traditional patterns from an Indigenous community in western Mexico.