Hana Shalabi, a Palestinian woman on a hunger strike for 43 days, has been deported to the Gaza Strip after ending her fast under a deal that has been criticised by Palestinians.
Shalabi has been protesting against her detention by Israel without charge.
Witnesses and Palestinian officials told the AFP news agency that Shalabi entered Gaza via the Erez border crossing, and was transferred by ambulance to a local hospital for tests.
Shalabi, who met relatives on the Israeli side of Erez before entering Gaza, said she was "very happy to be in my country with my people".
But, she added, the encounter with her family - from Jenin in the West Bank - was very difficult.
"I was shocked meeting my family, and they were shocked to see me," she told the media on the Gaza side of Erez. "The meeting with my family was very difficult."
Shalabi was received in Gaza by approximately 100 people bearing her picture and calling out her name. Officials from the Islamic Jihad and Hamas movements were also there.
Sivan Weizman, Israel's prison services spokeswoman, said Shalabi, who ended her hunger strike on March 29, was transferred in a regular vehicle, and that she had no details on her condition.
Shalabi began her hunger strike after she was arrested on February 16 and held without charge. She was hospitalised on March 19, after 33 days without food, with doctors saying she had lost 14kg and her pulse was "feeble".
On March 29, Palestinian authorities announced that Shalabi had agreed to a deal with Israel under which she would be released and deported to Gaza for three years in exchange for ending her hunger strike.
'Forced to accept'
The deal has been criticised by rights groups and the Palestinian prisoners affairs ministry, which said she had been forced to accept the arrangement.
But in a statement released on Sunday through her lawyer, Jawad Bulus, Shalabi insisted she had agreed to the deal voluntarily.
'To my dear family and my people and all the free people in the world, I thank you for your efforts and I appreciate everything you did for me and for the prisoners," she said.
"I hope that you will understand my position and my decision, which was taken freely."
"I chose to be transported to Gaza, which is half the homeland, and to be with my family and people there for three years," she said.
"With no guarantees that she or her family will be permitted to travel, her expulsion could essentially become an extension of her previous isolation"
- Addameer and Israel's Physicians For Human Rights-Israel
"After that I will go back to my home in Jenin and to my family. I hope that my decision will be respected and that we will continue to support together those who are fighting their battles for the homeland and for the prisoners," said Shalabi.
Palestinian prisoners group Addameer and Israel's Physicians For Human Rights-Israel, both of which worked on Shalabi's case, expressed concern about the deal, in a joint statement on Sunday.
They noted that their officials, as well as Shalabi's relatives, were denied access to her during the final days of her hunger strike.
And they warned that "aspects" of the deal "are fundamentally at odds with international law".
"With no guarantees that she or her family will be permitted to travel, her expulsion could essentially become an extension of her previous isolation from her home and family while in prison."
The International Committee of the Red Cross (ICRC) said in a statement issued in Geneva that it was not involved in the negotiations between Shalabi and the Israeli authorities "and is not aware of the details of the arrangement."
However, the organisation said it "urges the Israeli authorities to comply with international humanitarian law ... which prohibits Israel, whatever its motives, from forcibly transferring Palestinians to another territory."
The statement added: "On purely humanitarian grounds, the ICRC did facilitate a visit between Ms Shalabi and her relatives, which took place today at the Erez crossing."
Israel had previously held Shalabi for 25 months but released her in October last year under a prisoner swap deal with Hamas, which controls Gaza.
Shalabi was one of about 300 Palestinian prisoners being held in Israeli jails under administrative detention orders, which allow a court to order an individual to be detained for renewable periods of up to six months at a time.
Her action followed a hunger strike undertaken by another Palestinian prisoner, Khader Adnan, who also protested his detention.
Adnan refused food for 66 days, only agreeing to end his hunger strike after a deal was struck ensuring he would be released at the end of his four-month term.
In the wake of his hunger strike, dozens more Palestinian prisoners in Israeli jails launched similar protests, according to Palestinian and Israeli officials.