By Dan Collyns BBC News, Lima

A complaint has been made to the Spanish ambassador in Peru

The Peruvian Congress has made a formal complaint against Spanish airline Iberia after it allegedly discriminated against two indigenous congresswomen.

Maria Sumire and Hilaria Supa say staff prevented them from boarding a plane to Madrid on Saturday while allowing other passengers to go in front of them.

The women - who speak the indigenous language Quechua as their mother tongue - say staff mocked their Spanish.

A spokesman for the airline has denied any discrimination took place.

The women, who were both dressed in clothing typical of women from the Andean region of Peru, said staff told them the plane was full despite the fact they held reserved seats.

Ms Sumire said that when she complained - showing her diplomatic passport - the staff mocked the way she spoke Spanish, telling her she could complain to whoever she liked.

'Insulted'

Indignant at her treatment, she said if they as congresswomen were treated this way in their own country, how much worse must it be for fellow indigenous Quechua-speaking Peruvians.

A spokesman for Iberia denied any form of discrimination, saying they arrived after all the seats on the plane had been filled.

But the president of Peru's Congress, Mercedes Cabanillas, has made a formal complaint against the airline to the Spanish ambassador in Peru.

She said Congress felt insulted that two of its representatives had been discriminated against and it would not be tolerated.

Earlier this year, the two women made headlines in Peru and abroad when they announced they would only speak their mother tongue of Quechua in the Peruvian Congress.