A gay couple were left “very disappointed” after being told only one of them could board a flight early with their 19-month-old child – even though straight families were allowed to board together.

Jeff Cobb, his husband and his daughter were flying from San Francisco to Taipei with EVA Air on 1 September when the incident occurred.

As parents travelling with an infant they joined the priority boarding queue, but were told that only one parent was eligible to board the plane early.

Cobb wrote on Twitter: “My husband and I were told only one of us could join our 19-month-old in the family boarding group of EVA Air 27 from SFO on 9/1/18.

“I explained we were both the fathers of the child, and they said it was their policy that only one parent can board and the other has to wait in the normal line. Not having flown EVA before, I accepted it and let my husband and child go while I boarded later.”

However, when Cobb eventually boarded, his husband said the policy didn’t seem to extend to heterosexual couples.

“When I met him on the plane, he said there were many other (straight) families all boarding together,” said Cobb. “I’m very disappointed that the EVA ground staff at SFO thinks it’s OK to separate same-sex families during boarding.

“I will definitely not be flying this airline again after this incident.”

EVA Air has since apologised and described the incident as a “misunderstanding”. A spokesperson for the airline said: “EVA Air and most especially our San Francisco International Airport team sincerely apologise to all the passengers affected by this incident.

“It is our policy that passengers travelling with infants can have priority boarding.

“The policy does not limit the number of accompanying adults or specify the relationship to the infant.

“This unfortunate incident was due to misunderstanding.“

The spokesperson added: “Our San Francisco ground-handling agent understood that only one parent could board with an infant.