Fears are growing for UK holidaymakers who have been missing since the bomb attacks on the Egyptian resort of Sharm al-Sheikh which left 64 people dead.
Britain's ambassador to Egypt says a "number of Britons" may have died but a hospital manager in Sharm al-Sheikh said two Britons were dead.
Egypt's tourism minister says security is being revised. Meanwhile police are searching for six Pakistani nationals.
Concerned relatives of tourists should call the hotline: 020 7008 0000.
Egyptian police have distributed photographs of the six men being sought. They are believed to have been staying at the resort at the time of the triple bomb attacks.
Eight Britons were injured in the attacks, including a girl aged 14 and a 30-year-old man, who were both critically injured.
British embassy officials have already confirmed there are fears over two Britons staying at the Ghazala Gardens hotel, in Naama Bay, who have been reported as missing.
Fergus Stewart, general manager of the Hyatt Regency Hotel, said another young British couple in their 20s who had been guests were missing.
He said their family was due to fly in to search for them.
A Foreign Office spokeswoman said officials were working with Egyptian authorities to try to trace missing Britons.
She added: "As it stands at the moment, there could be a number of British deaths but we don't have official confirmation of figures."
Meanwhile, a seriously injured 16-year-old girl has been flown to the UK by air ambulance from Cairo.
A man in his 20s remains in a Cairo hospital with serious injuries.
One injured UK tourist left a hospital in Sharm al-Sheikh on Sunday, leaving three still there.
One British tourist, Gary Macleod, told the BBC that he and his partner Gillian had been woken by a "tremendous explosion" after the car bomb went off at the Ghazala Gardens, about half a mile away.
They ran down to their hotel's courtyard and shortly afterwards heard a smaller explosion "about 100 yards away".
"We felt the blast of the smaller bomb and within minutes we were seeing walking wounded coming back up," he said.
An estimated 9,000 Britons were staying in the resort
"We spoke to hotel staff that had immediately run down to the scene and there was one gentleman who'd seen some quite horrific things. We just tried to calm him down, and tried to give him a drink."
Mr Macleod was also caught up in the London bombings on 7 July. He was evacuated shortly after changing trains at King's Cross during his daily commute.
Ernest Stockley, 59, his partner Patricia Barr, 56, and their daughter, two-year-old Nichola, were among holidaymakers flown back to the UK on a special flight on Sunday.
They were asleep at the Ghazala Gardens hotel when the bomb went off.
Mr Stockley, a van driver from Prescott, Merseyside, said: "There was a terrific bang, we were shook out of bed and every piece of glass in the room exploded".
"All the window frames were blown in and the doors were blown off. Then we heard screaming.
"We had the child between us in bed. The cot was under the window. I looked at it later and it was half full to the top with shards of glass.
Foreign Secretary Jack Straw said there was no evidence of a link between the Egyptian blasts and those in London, but he said he could not rule it out.
He refused to advise against travelling to the country, saying: "We are already warning about a high risk of terrorism in Egypt."
Egypt Tourism Minister Ahmed El Maghreby told BBC Radio 4's Today programme that security procedures in Sharm El Sheikh were being revised.
"There is no doubt that some experience is gained from such as event," he said.