Forty-three reservists and former members of an elite Israeli army intelligence unit condemned alleged "abuses" of Palestinians in the occupied territories, in an open letter published on Friday.
The letter, addressed to Israel's prime minister, armed forces chief and head of military intelligence and distributed to media, said information gathered by Unit 8200 was used by civilian intelligence agencies to coerce Palestinians uninvolved in militant activity.
The signatories of the letter said they would refuse to be party to such acts in future.
"There's no distinction between Palestinians who are, and are not, involved in violence," an English language copy of the letter says.
"Information that is collected and stored harms innocent people. It is used for political persecution and to create divisions within Palestinian society by recruiting collaborators and driving parts of Palestinian society against itself."
"We cannot continue to serve this system in good conscience, denying the rights of millions of people," the 43 soldiers and officers wrote.
The signatories gave just their ranks and first names or first initials.
"Those among us who are reservists, refuse to take part in the state's actions against Palestinians," the letter, seen by AFP said.
"We call for all soldiers serving in the Intelligence Corps, present and future, along with all the citizens of Israel, to speak out against these injustices and to take action to bring them to an end."
The letter, published less than three weeks after the Israeli military's fierce military offensive against Palestinian militants in the Gaza Strip, slammed the "collective punishment of inhabitants" of the coastal territory.
- Army questions their motive -
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It did not specifically mention the July-August war which took the lives of more than 2,100 Palestinians, most of them civilians, and 73 people on the Israeli side, 67 of them soldiers.
The army on Friday questioned the accuracy and motivation of the protesters' accusations.
"The Intelligence Corps has no record that the... violations in the letter ever took place," it said in a statement.
"Immediately turning to the press instead of their officers or relevant authorities is suspicious and raises doubts as to the seriousness of their claim."
Members of Unit 8200, considered among Israel's best and brightest, carry out electronic communications monitoring and surveillance, similar to work performed by the US National Security Agency and Britain's GCHQ.
The unit is one component of the broader military intelligence corps and shares information with Israel's civilian intelligence agencies.
A former commander of the unit, reserve Brigadier General Hanan Gefen, accused the letter's authors of a grave breach of trust.
"If this is true and if I were the current unit commander, I would put them all on trial and would demand prison sentences for them, and I would remove them from the unit," he was quoted as saying by Maariv newspaper on Friday.
"They are using information that reached them in the course of their duties to promote their political position."
One of the signatories, speaking on condition of anonymity, told top-selling Yediot Aharonot newspaper: "I think that all of us who signed the letter did so because we understood that we are unable to sleep well at night."
Most Israeli men perform three years of compulsory military service after school, and women two years, followed by regular spells of reserve duty for years afterwards.