Tony Blair's sister-in-law is stuck in the Gaza Strip today after entering the territory without a permit as part of a human rights mission.

Lauren Booth, sister of the former Prime Minister's wife Cherie, has been refused entry into both Israel and Egypt after arriving in Hamas-run territory by boat from Cyprus 12 days ago.

She travelled to Gaza as part of a human rights mission called the Free Gaza Movement, which aims to draw attention to the international blockade of the territory.

Israel says it is under no obligation to allow her entry so she can fly home from Tel Aviv because she had entered Gaza without permission. Egypt, meanwhile, claims it refused her entry through its Rafah crossing point because it had been open for humanitarian traffic only.

“It could be days, weeks or years before I can leave, depending on the mood of the Israeli authorities,” she told The Times, adding that she was upset she could not be with her children as they began the school year.

Ms Booth said that, after Israel's refusal, she and three others spent hours at the Rafah crossing waiting to cross before Egypt also refused her passage.

“We were down there on Saturday in an overheated bus for more than two hours with over 100 people in 90 degree heat,” she said, adding they spent nine hours in total on Saturday and 13 hours on Sunday trying to cross into Egypt.

Yigal Palmor, an Israeli foreign ministry spokesman, said: “No country in the world is required to allow a foreign national to enter its territory."

An Egyptian official, who asked to remain anonymous, said: "She was not refused. The crossing was only opened for humanitarian cases that were coordinated in advance by the PA [Palestinian Authority]. Egypt is welcoming anybody at anytime, but not at the Rafah crossing point – which according to a 2005 agreement is being [kept] closed."

Ms Booth broke an Israeli naval blockade on the Strip as part of a human rights mission. The two boats on which she and her party travelled returned to Cyprus a few days later, leaving behind 11 activists to do humanitarian work. Only Ms Booth and three others are trying to leave.

“This is a punishment, and it’s a warning to the people who may in the future want to come on the boat: imprisonment in the largest internment camp in history," she said.

Ms Booth said she had visited several refugee camps while in Gaza and took part in a protest to help an old woman who had a spinal tumour to get access to a hospital in Jerusalem.

As she remained stranded in Gaza, her brother-in-law - who is now international peace envoy to the Middle East - was holding meetings only a few miles away with officials in Israel. His assistant Matthew Doyle said that the British Consulate was working hard to provide her with assistance.

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