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Israeli-Russian researcher Elizabeth Tsurkov, who went missing in Iraq in March, appealed for her release in a video published late on Monday on Telegram Channels linked to Iran-backed Shiite militias.
Ms Tsurkov travelled to Iraq for research for her doctoral degree at Princeton University in the US but had not been seen since March, the University said after her kidnapping.
Her disappearance was not widely known until Israeli Prime Benjamin Netanyahu's office issued a statement in early July, saying she was being held by Kataib Hezbollah militias.
The influential militia has denied the accusation.
Social media accounts linked to militias accused her of being an agent to Mossad and CIA in Iraq and Syria, but offered no evidence for the claim.
“I have been in the prison for seven months now,” Ms Tsurkov, 37, said in the video, which ran for more than four minutes in Hebrew with Arabic translation.
“There is nothing to secure my release, I’m a in a difficult situation.
"To my family … work to win my release as soon as possible in order to return to them."
While in Syria, her role was to establish a connection between Israel and the US-backed Syrian Democratic Forces, she said.
In Iraq, she worked to co-ordinate pro-democracy 2019 protests that swept through Baghdad and key provinces in southern the country, Ms Tsurkov said.
"We worked to deepen the differences in order to create a Shiite-Shiite warfare inside Iraq," she said.
In what is considered to be proof that the video is new, she made reference to the Israel-Gaza war that began last month.
The Israeli military operation and siege of the enclave have thus far killed more than 11,000 people, most of them civilians.
She said this policy "will lead to catastrophe and the continuation of war", and "this war must be stopped".
The National could not independently verify the authenticity of the video.
Israeli citizens are not allowed to enter Iraq and the Iraqi Parliament passed a law last year criminalising any ties with Israel.
The law also applied to foreigners working in Iraq, possibly putting Ms Tsurkov at risk.
Her research focused on the Levant and particularly the Syrian civil war, according to New Lines magazine, a publication of the Newlines Institute for Strategy and Policy think tank in Washington where Ms Tsurkov was a fellow.
The magazine said she was a passionate critic of Israel, while also aiming strong criticism at Iran's allies in the Middle East.