By Noah Browning

RAMALLAH, West Bank (Reuters) - Two Palestinian prisoners whose hunger strike stoked clashes in the West Bank have ended their protest after Israel agreed to release them in May, a Palestinian official said on Wednesday.

The men were among four prisoners held without formal charge in an Israeli jail who have refused to eat for between three and six months.

Their worsening state, coupled with the death of another Palestinian in detention on Saturday, fuelled the violence in which at least six Palestinian protesters were shot and badly wounded, less than a month before U.S. President Barack Obama is due to visit the West Bank town of Ramallah and Jerusalem.

"Jaafar Izzedine and Tarek Qaadan have paused their hunger strike," said Qadura Fares, head of an advocacy group for Palestinian prisoners.

He confirmed that Israel had agreed to release them on May 21 and said an Israeli court was expected to ratify the deal early next month.

Israel holds 178 Palestinians as "administrative" detainees - jailed without trial as suspected militants for renewable three to six-month terms based on classified evidence.

An Israeli official with the Prisons Authority confirmed that Izzedine and Qaadan had stopped their fast but did not comment on whether a deal was reached to free them.

Palestinian and Israeli officials are still seeking a deal for the other two prisoners, Samer al-Issawi and Ayman Sharawneh.

They are being treated in Israeli hospitals after months of intermittent hunger strikes against their re-arrest after having been freed in a 2011 prisoner swap with Israel.

"The Israeli side has begun dialogue today to find a solution to this issue, but so far they have not presented an acceptable offer," the Palestinian minister of prisoners, Issa Qaraqa, told reporters, adding that Issawi and Sharawneh had refused an offer to be freed and deported.

At least six Palestinian protesters were wounded this week in clashes with Israeli troops after Arafat Jaradat died while being interrogated in an Israeli jail on Saturday.

A United Nations rights envoy called for an independent inquiry into Jaradat's death on Wednesday. U.N. Secretary-General Ban Ki-moon appealed for calm and said Israel should either put the Palestinians in its custody on trial or release them.

Palestinian officials said the corpse of Jaradat, who was 30, bore signs of torture, but Israel has said the autopsy was inconclusive.

(Additional reporting by Ali Sawafta in Ramallah and Nidal al-Mughrabi in Gaza; Editing by Tom Pfeiffer)