A number of Britons detained in Israel after soldiers stormed an aid convoy they were part of are due to return to the UK, the Foreign Office has said.
A spokesman said "several" of the 41 Britons held had agreed to be deported and it would "seek clarification" on the fate of those who had not.
Deputy Prime Minister Nick Clegg has questioned whether it was in Israel's interest to "confine" so many people.
Activist Hasan Nowarah, from Glasgow, has already been returned to the UK.
The Foreign Office says it understands any Britons who do not agree to be deported will be forcibly returned.
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 Nowarah, originally from Ramallah, said he was the first to be sent home because he had injured his leg during the raid.
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 civilan, 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.
Earlier he said: "As we finish our prayer all we can hear is people screaming.
"We looked at the Marmara ship, we can see the Israeli helicopters dropping soldiers on the top and screaming and shouting and bullets fired all over the place."
One British national is still being treated in an Israeli hospital and the other 40 are being held in Beersheva prison.
Friends and relatives of those caught up in the raid have complained about the lack of communication.
Rachel Bridgeland, whose partner Peter Venner, 63, from Ryde, Isle of Wight, was on the convoy, said more pressure should be applied on Israel.
She said: "It's absolutely terrible not knowing what has happened to him and it's terrible that the British government hasn't done more but they don't want to fall out with Israel."
Sarah Colborne, campaign and operations director for the Palestine Solidarity Campaign (PSC), is also among those being held.
PSC general secretary Betty Hunter said: "Those held illegally by the Israeli government have committed no crime, they have simply attempted to avert a humanitarian disaster by bringing much-needed medical supplies into Gaza."
Israel maintains the commandos were attacked first, saying its soldiers were attacked 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.
Mr Clegg, who campaigned against the Gaza blockade before joining the coalition government, told BBC Radio 4's Today programme Israel had "every right" to protect its people from terrorist threats.
But he added: "Is it in Israel's long-term security interest to have so many people confined in that way?
"No, I don't think it is and what I ask my Israeli friends and Israeli politicians and officials I meet is: 'What's the strategy, where do you go next, how are you going to secure in the long term, not just day to day, the security which you rightly crave?'"
He also said the blockade was a "humanitarian catastrophe" and neither sustainable nor tenable "in its present form".
Foreign Secretary William Hague said the strength of demand for lifting the blockade for aid and commercial goods was "greater than ever before" and that the restrictions might even damage Israel's long-term security.
He said consular officials had visited 29 British nationals but that there was some confusion over the nationalities of other detainees.
Prime Minister David Cameron's spokesman said the loss of life was deplorable but added it had advised against the flotilla because of the risks.
He said: "Our concern is now British nationals who are currently detained... our concern is that they are unharmed and are brought back as quickly as possible."
Former prime minister Tony Blair, a Middle East envoy, told the BBC the search for peace must continue, despite events.
He said: "We have got to continue the proximity talks that we want to turn into full blown direct negotiations over all the core issues between the Israelis and the Palestinians."
He added any internationally-led inquiry must be "full and fair and impartial".