A German court has upheld the right of Kuwait Airways to refuse to carry Israeli citizens on any of its flights.

The court in Frankfurt rejected an Israeli passenger's discrimination claim against the airline after he was barred from a Frankfurt-Bangkok flight in 2016 despite having a valid ticket.

The national carrier had based its decision on a Kuwaiti law from 1964 that forbids its citizens from doing business with Israeli citizens. Kuwait Airways then offered the Israeli a seat on a replacement flight.

The court ruled that it was not reasonable to expect the airline "to fulfil a contract if in doing so it committed a violation of the laws of its own country and thereby expected to be prosecuted there."

The German court said it did not have to decide whether the Kuwaiti law itself was reasonable or whether it could stand up to scrutiny under German or European law.

The court also rejected the passenger's claim for compensation, ruling that the German anti-discrimination law applied only to race, ethnic background or religion, not to a specific nationality.

The Israeli passenger's legal advisers denounced the decision.

"If a restaurant refused to provide service to someone because they were black, we would rightly be outraged and appalled," said Brooke Goldstein, executive director of the Lawfare Project.

"We wouldn't stop being appalled if, upon kicking him out, the restaurant offered him a voucher for the restaurant next door. That is the legal reasoning the judge seems to have used in this case."

"The statement by the court that my client was supposed to accept transportation on other airlines is nothing more than capitulating to anti-Semitic discrimination by Kuwait Airways," Nathan Gelbart, the Lawfare Project's German counsel, said.

"This is a shameful verdict for democracy and for Germany in general. This verdict cannot stand. We will definitely be appealing."

Frankfurt Mayor Uwe Becker also denounced the verdict, saying: "To my mind, an airline that practices discrimination and anti-Semitism by refusing to fly Israeli passengers should not be allowed to take off or land in Frankfurt, or at any other airport in Germany.

"This Kuwaiti law, that is deeply anti-Semitic and that forbids the transport of Israelis cannot be legal grounds for the violation of international standards."