* Prisoner's death has stoked West Bank tensions
* Five youths shot, badly wounded
* Violence erupts a month before Obama visit
Masked Palestinian gunmen fired in the air and youths clashed with police on Monday as thousands marched at the West Bank funeral of a prisoner following days of rioting that have stoked Israeli fears of a new uprising.
Israeli police shot and wounded five Palestinian youths during confrontations in Bethlehem and outside a West Bank prison, leaving one 15-year-old boy in a critical condition, Israeli and Palestinian medical sources said.
Arafat Jaradat's death in disputed circumstances in an Israeli jail on Saturday, together with a hunger strike by four other Palestinian inmates, have fuelled mounting tensions, a month ahead of a visit to the region by U.S. President Barack Obama.
On the roof of Jaradat's home in the village of Se'eer, masked Palestinian fired volleys of automatic gunfire into the air in tribute, as dozens of Israeli troops gathered on the outskirts of town.
"We sacrifice our souls and blood for you, our martyr!" mourners chanted.
Elsewhere other youths were wounded by rubber bullets and suffered tear gas inhalation during the latest in a week of clashes that have raised memories the Intifada, Arabic for uprising, which started in 2000 after Israeli-Palestinian peace talks failed.
A previous Intifada, in 1987-1993, led to interim accords and limited Palestinian self-rule.
Israeli Civil Defence Minister Avi Dichter, former chief of the Shin Bet intelligence service, warned a new uprising might start if confrontations with protesters turned deadly.
"The previous two Intifadas ... came about as a result of a high number of dead (during protests)," Dichter told Israel Radio. "Fatalities are almost a proven recipe for a sharper escalation."
The Israeli military said dozens of Palestinians threw stones at soldiers across the West Bank on Monday. Troops responded with teargas and stun grenades, the army said.
A source in the Israeli military said its forces had used live ammunition in some cases where they considered protesters a lethal threat.
Jaradat, 30, was arrested a week ago for throwing stones at Israeli cars in the West Bank.
Palestinian officials said he had died after being tortured in prison. But Israel said an autopsy carried out in the presence of a Palestinian coroner was inconclusive.
The U.S. State Department said American diplomats had contacted Israeli and Palestinian leaders and appealed for calm.
"All parties should seriously consider the consequences of their actions, particularly at this very difficult moment," deputy spokesman Patrick Ventrell told reporters.
Robert Serry, the U.N. coordinator for the Middle East peace process, called for "an independent and transparent investigation into the circumstances of Mr. Jaradat's death, the results of which should be made public as soon as possible".
Palestinian frustration has been fuelled by Israel's expansion of settlements in the West Bank, stalled peace negotiations and a rift between President Mahmoud Abbas's Palestinian Authority and the armed Islamists of Hamas who run Gaza and reject coexistence with the Jewish state.
"We have no choice but to continue the popular resistance and escalate it in the face of the occupation, whether it be the army or the settlers," Mahmoud Aloul, a senior member of Abbas's Fatah movement, told Reuters.
Abbas has said he will not allow a third armed Intifada. The president chaired a meeting of his top security officials as clashes continued into Monday night, instructing them "to preserve the safety and security of citizens," state media said.
"The Israelis want chaos... We will not allow them to drag us into it and to mess with the lives of our children and our youth," Abbas said.
Dichter said Israel had to tread carefully in dealing with protests, accusing the Palestinians of trying to portray themselves as victims before Obama's visit.
"I don't think the Palestinian Authority will gain from an Intifada, just as it didn't achieve anything from the first or second Intifadas," he said.
"But I would say that, after conducting themselves with poor and warped thinking over the years, they don't always recognise what's in their best interests."
Israel demanded on Sunday that the Palestinian Authority curb the protests.
"They (the Palestinians) are trying to drag us to a situation where there will be dead children," Dichter said.
Palestinians have rallied to the cause of the four hunger-strikers, two of whom are being held without trial on suspicion of anti-Israeli activity.
Israel killed more than 4,500 Palestinians in the second Intifada. More than 1,000 Israelis were also killed, half of them in Palestinian suicide attacks mostly against civilians.