All the Britons who were held after Israel's raid on the Gaza aid flotilla have been accounted for, Foreign Secretary William Hague said.
He also told MPs 34 Britons were on board, rather than 37 as first thought.
Most of the Britons are flying home, many via Turkey, as Israel deports nearly all of the 682 detainees.
Briton Sarah Colborne, who was on the flotilla and has returned to the UK, has disputed Israel's tally of nine dead, claiming more were missing.
Speaking at a news conference held on Thursday in London, she said the official figure of those killed in the incident would rise.
Ms Colborne, campaign and operations director for the Palestine Solidarity Campaign (PSC), said those on board were aged between one and 89.
She described the raid as "a crime against humanity" and said she hoped the deaths of her fellow activists would serve as a wake-up call for UK and international governments to pressure Israel to end its blockade of Gaza.
Ms Colborne also described the siege on Gaza as "illegal, inhumane and immoral".
Speaking earlier to the BBC, she said: "I couldn't even count the amount of ships that were in the water. It was literally bristling with ships, helicopters and gunfire. It was horrific, absolutely horrific."
"I mean the whole thing was horrific, it was absolutely horrific what happened."
Some of the Britons who are still in Turkey told the BBC in Istanbul they wanted to stay for the funerals of those killed in the raid.
The BBC's Jonathan Head said: "A lot of them are saying although they want to get home, they want to stay here for a day or two more for the funerals of those who died."
According to Turkish media, eight of the dead were Turks and the other was a US national of Turkish origin.
Our correspondent said some people were pretty emotional and still very distressed by their ordeal, holding hands as they listened to speeches by fellow activists.
On Wednesday Prime Minister David Cameron called the raid "completely unacceptable", saying he deplored the loss of life.
In his first Commons question time, the prime minister said everything should be done to prevent it happening again.
And the foreign secretary said he was concerned at the raid taking place in international waters.
None of the Britons was currently believed to have been involved in any violence against Israeli servicemen who boarded the ships, Mr Hague told MPs.
Nine activists died when Israeli commandos boarded the six-ship convoy on Monday, prompting increased international pressure on Israel to lift its blockade of the Gaza Strip.
Mr Cameron told the Commons: "We should do everything we can to make sure this doesn't happen again.
"Friends of Israel - and I count myself a friend of Israel - should be saying to the Israelis that the blockade actually strengthens Hamas's grip on the economy and on Gaza.
"And it's in their own interests to lift it and allow these vital supplies to get through."
He added: "We should do everything we can through the UN, where resolution 1860 is absolutely clear about the need to end the blockade and to open up Gaza."
Acting Labour leader Harriet Harman called for the blockade to end and added: "This is a tragic loss of life which has angered the Palestinians and dismayed friends of Israel too."
Earlier, Deputy Prime Minister Nick Clegg questioned whether it was in Israel's interest to "confine" so many people.
Activist Hasan Nowarah, from Glasgow, said he was the first to be sent home because he had injured his leg during the raid.
Originally from Ramallah, he runs the Glasgow-based group Justice for Palestine and was in one of the smaller ships in the convoy.
"The minute they landed into our vessels they were shooting and killing innocent people," he told the BBC.
"We were in the international water, we were not a threat of any kind to the Israeli civilian, government or army."
He said an Israeli soldier hit him on his back and leg with his gun.
"We were unarmed, all we had were the chairs and tables we were sitting on to defend ourselves from the Israeli guns," he said.
Israel maintains the commandos were attacked first, saying its soldiers were confronted with "knives, clubs and other weapons" when they landed on the Mavi Marmara and had opened fire in self-defence.
Video clips show activists wielding a baseball bat and other objects, although some witnesses say they were acting in self-defence.