A second Briton has been confirmed dead in the bombings in the Egyptian resort of Sharm al-Sheikh on Saturday.
Victims Keri Davies and his American girlfriend Kristina Miller were en route to Australia
The victim has not yet been named. The only Briton previously confirmed dead was Keri Davies, 29, of Fareham, Hants.
The Foreign Office said it believed "a further eight people were involved and are likely to have been victims".
The families of Jez Lakin, 28, and Annalie Vickers, 31, on Tuesday said they believed it was likely the pair were among the 64 killed in the blasts.
The Foreign Office could not confirm if either Mr Lakin or Ms Vickers was the second Briton to be confirmed dead.
It said it had originally thought nine people could have been involved as victims, in addition to the two confirmed deaths.
However, on Thursday morning it was confirmed that one of the missing was alive.
Officials have said the death toll could rise as high as 88, following the blasts outside two hotels and a market in the town shortly after 0100 local time on Saturday (2300 BST on Friday).
The Lakin and Vickers families said in a statement issued through the Foreign Office that they believed their loved ones had been killed.
It added: "The response of the Egyptian emergency services and those who assisted at the scene of the explosions has been excellent. They acted with dignity and respect.
"We would like to add that the Egyptian people have been a great comfort to us. We know that many of them lost loved ones. Our hearts are with them also."
Mr Lakin was from Nottingham, and Ms Vickers from Northampton.
Help from public
The British ambassador to Egypt, Sir Derek Plumbly, has said the families of most of the missing are in touch with the embassy and several have flown to the resort.
Eight Britons were wounded in the attacks, including a girl aged 14 and a 30-year-old man who were both critically hurt.
Police have called on the public to help them verify the precise number of British victims.
"Officers urgently need help from those who originally reported family members missing, but who now know that those people are safe and well," said a Foreign Office spokeswoman.
She said these families should call the helpline number so their relatives can be ruled out of police inquiries.
Concerned relatives of tourists should call the hotline: 020 7008 0000.