"We received a message on Thursday from prisoners being held in [Israel's] Hadarim Prison stating that Sheikh Adnan had embarked on a weeklong hunger strike," Adnan's family said in a statement.
"His hunger strike is meant to protest the six-month extension of his administrative detention – without trial or charge – for the second time," the family asserted.
Adnan made headlines in late 2011 when he went on a 60-day hunger strike to protest Israel's "administration detention" policy. Several other Palestinian detainees also in administrative detention had followed suit.
Israel's administrative detention policy allows the self-proclaimed Jewish state to hold Palestinian prisoners indefinitely without trial or charge.
Administrative detention orders can range from one to six months in length and can be extended by up to five years by Israeli military prosecution authorities.
In February of 2012, a deal was reached between Adnan's lawyers and Israeli prosecutors for his release.
Under the deal, Adnan halted his hunger strike in exchange for his four-month detention being counted from the day of his arrest and a promise by Israeli authorities not to renew his administrative detention.
He was finally released on April 17, 2012.
But Israeli forces re-arrested Adnan last July without leveling any formal charges against him, saying merely that he had been detained for "threatening regional security."
According to official Palestinian figures, around 7,000 Palestinians continue to languish in jails throughout Israel.