"We offer our deepest condolences to her family and loved ones. We are urgently gathering more information about the circumstances of her death and will have more to say as we learn more," State Department spokesman Matthew Miller said.

He identified the woman as Aysrnur Egzi Eygi and called her death "tragic," without immediately assigning responsibility.

Meanwhile,Turkey also condemned the "murder" of the pro-Palestinian US activist, who also had Turkish citizenship, saying she had been killed by "Israeli occupation soldiers".

The foreign ministry said in a statement that it had learned "with great sorrow that our citizen named Aysenur Ezgi Eygi was killed by Israeli occupation soldiers in the city of Nablus", adding that it condemned the "murder".

Rafidia hospital director Fouad Nafaa in Nablus said a US citizen, an activist in her mid-20s, died from a "gunshot in the head" after being admitted Friday.

Witnesses and Palestinian media reported that the woman was shot by Israeli troops while attending a demonstration against  settlement expansion in the Palestinian town of Beita, north of Ramallah in the Israeli-occupied West Bank.

The official Wafa Palestinian news agency said she was an activist in a campaign to protect farmers from Israeli settler violence.