The daughter of a Swansea cardiologist is blaming British Embassy staff for him being stuck in Gaza.
Ahmed Sabra, a UK citizen who holds a British passport, was visiting Gaza with family when the conflict started.
They waited three weeks for the Egypt crossing to open and, while his loved ones were on the approved list of British nationals, Dr Sabra was not.
The Foreign Commonwealth and Development Office said they had no control over the authorities involved.
Thousands of foreign nationals have been making the same trip but the only those named on a list published daily by the Gaza Border Authority are allowed to cross over. Those on the list must be cleared by both Egyptian and Israeli authorities.
Dr Sabra's daughter Haya, 20, said embassy staff didn't act fast enough to help her father who, after a further three days' wait, was still not added to the list.
Instead, he and three other UK residents were loaded onto a bus and sent back to the Gaza side on Tuesday.
"We were assured by the embassy that those four people on the bus would not go back to Gaza," said Haya.
"The British government team arrived 20 minutes too late to save them.
"They weren't there - if they had been this would not have happened."
The BBC team in Gaza spoke to Dr Sabra on Wednesday after he had crossed back over the border.
He claimed embassy staff could still have done something while the bus waited for hours at the Egyptian side of the Rafah Crossing, but they arrived too late.
"They (Egyptian officials) told the two guys from the British Embassy, 'We gave you five hours to sort this out so that your citizens are clear to enter, you didn't do anything'," said Dr Sabra, adding that despite his journey being delayed until the following morning, subsequent chances were also missed to rectify the situation.
"We were calling everyone from the British Embassy, but nobody turned up to the crossing.
"In the end the officials said, 'We are sorry, we have to send you back'.
"'Your name is not on the list and your embassy needs to sort this out'."
He said he believes the UK government should "do their duty to protect me".
"I am a British citizen and I don't believe they did enough, I don't think they even did the minimum.
"The British Embassy sent me back to Gaza - the most dangerous place in the world now.
Dr Sabra's medical colleagues have written a joint letter calling on the UK government to do more to help him, and a petition urging the FCDO to do more has been signed by more than 4,600 people.
Haya, along with her mother, sister and younger brother, waited in a hotel at Cairo International Airport for their father, but Egyptian officials only let them stay in the country for 72 hours and they were put on a flight back to the UK on Thursday evening.
Her last contact with her father was this morning when he urged them to get on the plane.
"I don't know where he is, I don't know if he is safe, I don't know if he has water, if there is bombing nearby," she said.
"I don't want to go back to the UK. I don't know how I am supposed to go back without my dad, to this shameful government, knowing they sent him back to a death trap."
A FCDO spokesperson said: "We're working round the clock to ensure all British nationals in Gaza who want to leave are able to.
"This involves submitting all details of British nationals and eligible dependants to the Israeli and Egyptian authorities.
"The authorities then review all cases and give permissions to cross.
"We remain in regular contact with British Nationals in Gaza to provide them with the latest information, and UK teams are forward deployed to the border to receive anyone leaving."