Police in Israel have arrested an Israeli citizen who entered Gaza with a group of pro-Palestinian activists.

Jeff Halper, a US-born Israeli citizen, was arrested after he entered Israel through the Erez border crossing.

He is accused of breaking Israel's law forbidding its citizens from entering the Gaza Strip.

Mr Halper was part of an international group of protesters who entered the Gaza Strip by boat to challenge Israel's blockade of the territory.

Israel imposed a blockade on Gaza in June 2007 when the militant group Hamas took control of the territory by force.

Since then, Israel has allowed in little more than basic humanitarian aid as a means of isolating Hamas and persuading militant groups to stop firing rockets into Israel.

The closure of Gaza's borders by the Israeli and Egyptian authorities has also meant that very few Gazans have been able to leave.

Activists

Mr Halper spent three days in Gaza with the group of about 40 activists from 17 countries before crossing into Israel.

"He is being questioned at the police station in Sderot for entering the Gaza Strip in defiance of a military decree banning Israeli citizens from doing so," said Israeli police spokesman Micky Rosenfeld.

The activists on board the boats included Lauren Booth, sister-in-law of UK former Prime Minister Tony Blair, who is now an international Middle East peace envoy. Also on board was left-wing Greek MP Tasos Kourakis.

Israel withdrew its settlers from Gaza in 2005, but it still controls its coast, airspace and borders, and, until a ceasefire with Hamas was agreed in June, carried out regular military operations in the territory.

However, correspondents say the truce has not improved the situation for Gaza's population, except to reduce the number of Israeli incursions and the number of rockets fired by Palestinian militants.