Montreal's transit authority says it will investigate a complaint from a professional soccer player who claims he was the victim of a "racist" language-based incident involving a subway employee.

A spokeswoman for the authority says it will investigate after receiving a formal complaint on Wednesday, while Montreal Impact midfielder Miguel Montano publicly bemoaned his treatment.

The 20-year-old Impact reservist started by calling Montreal a racist city as he described the incident, but the Colombian-born player later backpedalled, and apologized if he offended people in the city.

Montano said in a pair of tweets that he was unable to buy a ticket to ride Montreal's metro system because he didn't speak French.

The Colombian-born soccer player alleges that when he tried to converse with a ticket-taker in English, he was told that he needed to speak French and his money was returned to him.

"They are so racist in Montreal," he wrote Wednesday on Twitter, in Spanish. "They didn't want to sell me a ticket to let me in the metro because I don't speak French."

He later added that the ticket-taker told him: "'If you live in Montreal, you need to speak French.' I spoke to him in English and he said NO [in] French and he gave me back my cash."

Several hours later, after the story had appeared in local media, the soccer player toned down his attack on the city.

Unacceptable situation

Montano said in the later tweets that he had experienced an unacceptable situation that made him very angry, and that's what prompted him to write his comment. He apologized if he offended anyone.

"Montreal is not a racist city," he added.

A spokeswoman for the transit authority said it received a complaint.

"Now that the compliant has been filed, we'll take the time to investigate the incident thoroughly," Marianne Rouette said.

Speaking in general terms, Rouette said there's a zero-tolerance policy for racism and transit employees know it.

As for the complaint about language, Rouette said that the transit system is governed by the province's French Language Charter.

That means no public employee is forced to speak any language other than French, although many employees happen to be bilingual or multilingual and can choose to speak other languages, she said.

A spokesman for the Montreal Impact told The Canadian Press he would comment later Wednesday, while confirming that a complaint had been filed.