All of the Palestinians in Israeli prisons -- about 4,500 people -- took part in a hunger strike Sunday, and crowds protested in the streets of the West Bank as Palestinian officials called for an international investigation into an inmate's death.

A Palestinian official also sent a warning to U.S. President Barack Obama, who plans to make his first trip to Israel as president next month.

"If President Obama wants to visit the region peacefully, he should exert pressure on Israel to release the prisoners -- especially the ones who are on hunger strike -- or else he will visit while Palestine is on fire," Palestinian Minister of Prisoner Affairs Issa Qaraqe said.

Speaking at a news conference in Ramallah, Qaraqe demanded an international investigation.

Israel said doctors had worked to save the inmate, who was suffering from previous injuries. The prisoner, Arafat Jaradat, 30, died Saturday.

"The martyr Jaradat was subjected to extreme torture which led to his death, and there are no indications that he died from cardiac arrest as the Israeli occupation authorities claimed," Qaraqe said Sunday. He added that "signs of beating and torture appeared on his limbs, neck, and spine, and blood clots appeared around his mouth and nose."

He cited information from a Palestinian doctor who was present for the autopsy in Tel Aviv.

But the Israeli Health Ministry said the autopsy showed "no signs of external damage ... except the signs of cardiopulmonary resuscitation (CPR) and a small spot caused by an abrasion on the right breast."

There were blood clots in the muscle -- one on the shoulder and one on the side of the right breast and on both elbows -- and two broken ribs, which could have been caused by the CPR, the ministry said in a statement.

"There is nothing apparent from the first findings that indicate the cause of death," it added. Other tests are pending.