A search is under way for a Carlow woman who is missing in Madrid since last Thursday.

Martha and Mary Osaro, 26-year-old twin sisters, went missing in the Spanish capital after celebrating their birthday, according to a Spanish missing persons organisation.

The Asociacion Sosdesaparecidos said the pair were last seen in the Centro, La Latina area of the city.

The two women are described as being 1.75m (5'8) tall, with dark eyes and dark wavy hair.

In a Facebook post, their older sister said the two women have been living in Madrid "on and off" for the past five years.

She added that Mary Osaro has been found but Martha is still missing.

The Department of Foreign Affairs have said it is aware of the case and is providing consular assistance.