A fan was forced to remove her Ukrainian flag by the chair umpire during the Cincinnati Open ©Getty Images

A fan was forced to remove a Ukrainian flag from tournament grounds at the Cincinnati Open by officials during a match between Russian players Anna Kalinskaya and Anastasia Potapova.

One of the athletes complained to the chair umpire Morgane Lara about the fan, prompting the referee to come down from her chair to speak to the spectator, who ultimately left the court.

The fan was approached on the grounds by the tournament's head of security who told her the flag was above regulation size.

"Per the Western and Southern Open's bag policy, as stated on the tournament's website, flags or banners larger than 18 x 18 [inches] are prohibited," a spokesperson for the tournament said, as reported by ABC.

"Therefore, the patron was asked to remove the flag from the grounds and, after doing so, was allowed to remain at the tournament.

Non-profit organisation Cincy4Ukraine has confirmed that it has made contact with a civil rights attorney to explore the possibility of the fan taking legal action for a breach of her first amendment rights.

"This is not Russia," the fan told television station Local 12.

"This is the United States of America.

"We had our Ukrainian flag, not doing anything crazy, distracting players, but wrapped around, sitting there peacefully and quiet."

She said the chair umpire told her: "'You need to put the flag away.'"

"The message I got was that it is agitating Russian players.

"I said, 'I'm not putting it away.'

"They kept playing for a minute or two.

"Then, they stopped the game again, and then the security guard came up to me and said, 'Ma'am, I’m going to call the cops if you won't leave.'"