Gaza City - The sister-in-law of former British prime minister Tony Blair accused Israel Wednesday of human rights violations because the country is not allowing her to leave the Gaza Strip via Israeli territory.

British journalist Lauren Booth has been stranded in Gaza for the past six days, along with three other pro-Palestinian foreign activists who had arrived a week earlier on two vessels that sought to peacefully challenge Israel's blockade of the strip.

The SS Free Gaza and the SS Liberty, which carried some 46 human rights activists, had reached Gaza on August 23, passing unhindered through Israeli-patrolled waters.

The vessels left Gaza on Thursday last week, returning to Cyprus, but Booth as well as an American, Irish and an Australian activist stayed behind.

They have tried since Friday to leave by land, but neither Israel nor Egypt has allowed them passage through Gaza's southern border crossing of Rafah and the northern border crossing of Erez respectively.

"Israel's siege on Gaza and the restrictions it places on everyone here, in this case on internationals, have to be a breach of international human rights, specifically the right to travel to your home and the right to travel to your country," said Booth.

She called Israel's restrictions on the entry of Palestinians aged 18 to 45 from Gaza into Israel via the Erez border crossing "institutionally racist."

"Putting restrictions on people in this way has created the largest internment camp in the world and it is controlled by Israeli guards," she told Deutsche Presse-Agentur dpa.

Booth, 41, said she had tried to leave Gaza not only via the Israeli-controlled Erez crossing, but also via the Rafah border with Egypt, where she was turned back by Egyptian border guards. She would not blame the Egyptian authorities, however, saying they acted out of "pressure put on them by Israel."

The half-sister of Cherie Blair said she had chosen not to return to Cyprus on board the vessels "to bear witness to the horrific and desperate situation here in greater detail."

Israel Radio quoted the Israeli military as saying that it was not allowing Booth entry into Israel via the Erez crossing, because she had entered the Gaza Strip "illegally."

An Israeli military spokesman and a Defence Ministry spokeswoman said they were checking the case.

Israel imposed its blockade on the Gaza Strip in response to rocket attacks from the area by Palestinian militants on its southern towns and villages. It has begun gradually easing the stringent sanctions on the entry and exit of goods and people since a fragile ceasefire took effect on June 19. (dpa)