Pavel Obiukh, a legally blind, disabled rights activist denied boarding on an S7 flight last month, demanded on Monday that the airline change its rules on disabled passengers and issue him a public apology or face a lawsuit.

S7, the second-largest airline in Russia, said it had only acted according to the law when it refused to fly Obiukh from Moscow to Kazan on Feb. 18.

The showdown between the airline and Obiukh, a member of Perspektiva, an organization that advocates for the rights of the disabled, is unprecedented in Russia, where people with disabilities routinely face difficulties gaining access to transportation, buildings and other facilities.

Obiukh said the incident last month was the first time that he had been denied entry to a plane even though he had notified the airline about his condition in advance.

"This is a case of open discrimination against disabled people," Obiukh said at a news conference.

S7 did not board Obiukh because he was flying without a human companion or a guide dog.

S7 said it had not been notified of Obiukh's disability beforehand, so it had no legal obligation to accept him on board. Obiukh bought his ticket through a travel agent, and the agent did not communicate to the airline that he needed special assistance, S7 said in a statement following the incident.

S7 rules are based on federal aviation regulations, which are dictated by the Transportation Ministry. The federal regulations say an airline is only required to carry a legally blind passenger if informed in writing about the condition in advance.

An S7 spokesman declined to comment on Obiukh's demands Monday.

S7 has received harsh criticism over the incident, which was reported by Russian-language media after Perspektiva distributed a statement through national news agencies before the plane even took off.

Independent aviation expert Oleg Panteleyev said the dispute smacked of a smear campaign against S7 because the criticism was aimed specifically at the airline rather than the federal regulations that it was following. S7 was right to reject an unaccompanied legally blind passenger, he said, because the passenger would require the full attention of a flight attendant in case of an in-flight emergency.

"This is definitely an attempt to rock the boat and direct public opinion against the airline," Panteleyev said.

Perspektiva's lawyer, Maxim Larionov, said the organization was sending a letter listing their demands to the airline and would file a lawsuit if there was no reaction within three days. Since Obiukh is seeking equal rights as a consumer, the Federal Consumer Protection Service would also be named in the lawsuit, he said.

Officials with the agency did not have an immediate comment Monday.

Another Perspektiva activist, Natalya Prisetskaya, who uses a wheelchair, sued S7 in similar circumstances last summer and was awarded 50,000 rubles ($1,383) after the court ruled that the airline had failed to properly inform passengers about its rules at the time of ticket sales.

State Duma Deputy Mikhail Terentyev said at Monday's news conference that Perspektiva also has asked Transportation Minister Igor Levitin to change the federal aviation rules.

"I would be more happy to resolve this without a lawsuit," Obiukh said. "The goal is for the airline to change its internal rules."

Russians with disabilities have long lobbied for legislative changes that would grant them equal access to services. Highlighting the difficulties that disabled people face on a daily basis, Monday's news conference started late because Terentyev, who uses a wheelchair, was not able to access the conference room on the second floor of the Interfax building. Two security guards eventually carried him up to the microphones.