JERUSALEM - The sister-in-law of former British Prime Minister Tony Blair said Wednesday that Israel and Egypt are preventing her from leaving the Gaza Strip, more than a week after she entered the territory in defiance of an Israel-led blockade.

Lauren Booth said she has been trying to leave Gaza since Friday, but was turned away at Israeli and Egyptian border crossings.

Booth was among 46 pro-Palestinian international activists with the Free Gaza Movement who sailed into Gaza waters on Aug. 23 to draw attention to Israel's blockade, which has prevented the area's 1.4 million Palestinians from traveling abroad and crippled the local economy.

Most of the protesters left Gaza on the same boats last Thursday and sailed to Cyprus, but Booth and several other activists chose to remain behind to do human rights work.

Booth said she has turned to British diplomats in the region to get her out of Gaza. "High-level diplomatic maneuvering is going on when none should be needed," she said.

She said she has not spoken to Blair, who now serves as the international community's Mideast peace envoy. Neither Blair's office nor the British Embassy in Tel Aviv returned calls seeking comment.

Israel and Egypt sealed Gaza's borders after the Islamic militant group Hamas violently seized power in June 2007. The sanctions have halted the movement of virtually all goods and people across Gaza's border. Israel considers Hamas a terrorist group.

Israeli Foreign Ministry spokesman Yigal Palmor said his government was still weighing whether to let her into Israel, but noted that Israel, like any country, has the right to decide who enters its territory.

"This is something she should have thought about before entering Gaza," he said. "Nothing was coordinated with Israel."

Egyptian officials were not immediately available for comment.