RAMALLAH, West Bank, July 14 (Ali Sawafta/Reuters) - Israeli troops shot dead a Palestinian man during clashes with stone-throwers in the occupied West Bank on Monday, both sides said, as tensions mounted over Israel's military offensive in Gaza.

Israel also detained dozens of Palestinians overnight in the West Bank and East Jerusalem, said activists, part of a crackdown on suspected militants stepped up last month after the abduction and killing of three Jewish seminary students.

A Palestinian witness said Munir Al-Badarin, 21, and other young men were throwing rocks at soldiers outside the West Bank village of Samoa when they were fired on by another army unit.

They (the Israeli troops) were hiding and ducking to the ground and when we showed up they rose from their place and began firing at us, the witness, who declined to give his name, told Reuters.

We escaped and soon we discovered that Munir was missing.

Ambulance driver Abdel-Mua'ez Al-Jarsawi told Reuters he was summoned to Samoa, where soldiers initially held him back as they tried to resuscitate Badarin, who was shot twice in the lower back. Jarsawi said he took Badarin to a nearby Palestinian hospital where the young man died.

An Israeli military source said Badarin was among three masked men spotted throwing rocks and bottles of paint at Israeli cars passing Samoa.

An Israeli army unit which lay in ambush noticed that they were about to throw a Molotov cocktail, and therefore engaged the suspects, which included live fire from which the Palestinian was killed, the military source said.

Israel's government intensified a crackdown on Islamist group Hamas, accusing it of kidnapping and killing the three Jewish students in the West Bank last month.

Tensions mounted further after a Palestinian youth was abducted in Jerusalem and burned alive in what Israeli police believe was a revenge attack by far-right Jews.

Israel launched a military offensive on Hamas-controlled Gaza last week, saying it was in response to an increase of rocket attacks from the territory.

Palestinians seek a future state in Gaza, the occupied West Bank and East Jerusalem, areas Israel captured in a 1967 war.

The Palestinian Prisoners Club, which advocates for Palestinians jailed by Israel, said 57 people were detained in the West Bank and East Jerusalem overnight, including 12 Hamas lawmakers. That brought the number of those taken into Israeli custody since last month to 1,071, the organization said.

The Israeli military confirmed 25 West Bank arrests.

In Gaza, Hamas spokesman Sami Abu Zuhri called the West Bank arrests a continued Israeli escalation against our people. (Writing by Dan Williams; Editing by Andrew Heavens)