If the Palestinians ever achieve a viable state, a young Israeli activist will be able to claim to have played her part. Hagit Ofran, a former student of Jewish history, spends her working day driving around the West Bank, monitoring the growth of Jewish settlements. Sometimes her findings translate into pressure on the Israeli government from abroad to stop the construction of further outposts. Ofran's official title is director of the settlement watch team of the dovish Peace Now organisation. Her job is to gather and collate information on how much building is going on.

During one expedition last month, she noted the presence of four new white houses looking like matchboxes on a hillside of the Alon settlement north-east of Jerusalem.

"It's not that one caravan will change the chances of Middle East peace,'' she says, "but another and another and another will determine whether we can have a two-state solution to the conflict or not.''

Israel's government now faces a decision over whether or not to extend a 10-month partial freeze on settlement building that expires in September. President Barack Obama's United States administration is pressing for the freez e to remain in place, but Prime Minister Benjamin Netanyahu's right-wing coalition partners want it scrapped to enable a wave of new building.

"If it is not extended then the freeze may have delayed a few hundred sites for months, but it will not have caused a real change,'' Ofran believes. "If work is restarted it might mean that the chances of peace are doomed, at least with this government.''

A fluent Arabic speaker, the 35-year-old activist is sometimes tipped off by Palestinians about new settler building, while some of the information she uses is garnered from planning meetings and official documents.

In March, she learned from the Jerusalem municipality's website that officials had given permits for settler building at the Shepherds Hotel site in the mostly Arab eastern part of the city. She did not keep the information to herself. News of the settlement project broke just before Prime Minister Netanyahu was to meet President Obama at the White House, contributing to the frostiness of that encounter.

Much of the settler building, although government sponsored, is illegal under Israeli law. An official Israeli government report in 2005 found that state bodies had diverted millions of shekels to build illicit outposts. Construction also runs counter to international commitments Israel has made to halt settlement building, for example in the 2003 international peace blueprint, the so-called "road map".

Ofran's work is not without its danger. Understandably, the settlers regard her as an unwelcome presence, and in the past has been evicted from settlements. After three years in the job, she is aware of the risks she is taking - she knows when to give a lift to hitchiking settler youths and above all when to make eye contact with settler guards.

"If they recognise me here we are in trouble,'' she says, navigating a rocky road near the settlement of Ma'ale Michmas, a few miles north-east of Jerusalem.

"I generally try not to make eye contact so there's less engagement and less chance they will recognise me. On the other hand, sometimes if you don't make eye contact it could be a problem because they'll know you're not from around here.''

Danny Dayan, chairman of the Yesha Council that represents most of the half-a-million Israelis who have moved to the West Bank, accuses Ofran of serving foreign interests.

"In a democratic state it is legitimate to follow the settlements,'' Dayan says. "The problem is that Peace Now does it with money that is from foreign sources, including from hostile sources. Her agenda is not objective.''

Adds Aliza Herbst, spokeswoman for the council: "It should be illegal for other countries to interfere in Israeli politics that way. They are obtaining information with funding from outside that is then used in a distorted fashion against the Israeli government's position at a very sensitive time."

Peace Now's settlement watch unit is receiving £93,000 in funding from the British government this year. Norway also supports its work.

Ofran is the grandaughter of the late philosopher, Yeshayahu Leibovich, one of the earliest Israeli critics of settling the West Bank after Israel's stunning victory in the 1967 Six Day War. He supported soldiers who refused to serve in the occupied territories and controversially warned that those who did so risked becoming "Judeo-Nazis.''

"I used to hear him a lot and my character was influenced by his thinking,'' Ofran says.

As her grandfather did, she believes Israel must withdraw from the West Bank, land inhabited by more than two million Palestinians, if it is to remain a state with a predominantly Jewish population and character.

"I see my self first of all as Jewish and only then as an Israeli and it is very important to me how the Jewish state is acting,'' she says.

"If we want to hold all the land then we must give the Palestinians full rights. So holding all the land means we will lose our independence as a Jewish people.

"I don't want to live in a state where there isn't a Jewish majority. I want to live in a Jewish state.''