An employee at Madrid Metro has been suspended for circulating a memo urging workers to keep an eye on "musicians, beggars and gays" to make sure they paid for valid tickets.
The memo was sent out to workers on Tuesday night (17 February) and Wednesday at the start of their shifts.
It listed stations including Sol and Las Rosas on line 2 where "musicians, beggars and gays" needed monitoring.
The worker in question, who has not been named, has been suspended from his duties pending an investigation.
Teodoro Pinuelas from the UGT trade union, which represents Metro employees, told El Pais: "I don't understand why it would assume that homosexuals wouldn't pay for their tickets and that they need to be monitored. Why not tall people, or blondes or those who wear glasses?"
The Metro authorities launched an investigation to find out if anyone in a senior position knew about the memo before it was distributed or could have changed the wording before it went out to employees.
Ignacio Gonzalez Velayos, Metro's managing director, tweeted: "We have opened an investigation and will determine who is responsible for the unfortunate memo."
LGBT group Colega Madrid said: "This is humiliating and discriminatory. It's clear discrimination and harassment due to sexual orientation."