Megiddo, Israel - The Palestinian Prisoners Club advocacy group said Monday that a teenager died in an Israeli jail, decrying a spike in custody deaths since the start of the Gaza assault.

In a statement, the group announced the death of Walid Khaled Abdullah Ahmad (17) in Megiddo prison in northern Israel in unknown circumstances.

Contacted by AFP, Israeli prison authorities did not immediately respond to a request for comment.

One of thousands of Palestinians in Israeli custody, Ahmad is the 63rd Palestinian to die in Israeli jails since October 2023, according to the Prisoners Club.

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The advocacy group said Ahmad, from the town of Silwad near Ramallah in the occupied West Bank, was detained on September 30. It was not clear what had led to his arrest.

The Prisoners Club said that a "growing number" of detainees have died in Israeli custody due to "systematic abuses" throughout the Gaza assault.

"This period has been the deadliest in the history of the Palestinian prisoners' movement since 1967," it said, referring to the year Israel seized Palestinian territories including the West Bank.

Rights groups including Israel's B'Tselem have documented numerous cases of deaths of Palestinians in Israeli prisons over the last 17 months.

B'Tselem has reported worsening detention conditions for Palestinians including "systematic mistreatment" and "torture" – which Israeli authorities have denied.

The Prisoners Club said in September there were at least 250 Palestinian minors in Israeli custody.

According to non-government group Defense for Children International Palestine, "each year approximately 500-700 Palestinian children, some as young as 12 years old, are detained and prosecuted in the Israeli military court system. The most common charge is stone-throwing."