By Nidal al-Mughrabi
GAZA (Reuters) - An Israeli air strike killed three militants in the Gaza Strip on Friday, the Islamist group Hamas said, hours after an overnight clash killed a fourth Palestinian gunman and wounded five Israeli soldiers.
It was the worst violence between Israelis and Palestinians in the coastal enclave since a ceasefire ended an eight-day conflagration in November.
There has also been a rise in shootings and clashes in the occupied West Bank in recent months, even as mediators push on with the latest round of U.S.-brokered peace talks - negotiations that observers say have shown little sign of progress.
The Israeli military said its aircraft targeted a tunnel inside the southern Gaza Strip used by militants bent on attacking Israelis, and accused Hamas, Gaza's ruler, of breaching the terms of the ceasefire.
A Hamas source said three of its men were in the tunnel at the time of the attack and were killed in the blast.
Hours earlier, one Palestinian militant was killed and five Israeli soldiers wounded when Israeli forces started destroying part of a separate tunnel they had uncovered last month stretching from Gaza into Israel.
Israel says the underground route ran for 1.7 km (1 mile) and was intended to let militants cross deep beneath the border fence and carry out surprise attacks.
Israeli media, citing a military source, said the Israeli soldiers in the tunnel had accidentally drilled into explosives planted by Hamas. The resulting blast wounded five of the soldiers and the Palestinian militant was killed in ensuing fighting, the reports added.
At a sermon before Friday prayers, senior Hamas leader Khalil Al-Hayya said the clash showed Hamas fighters were "alert and ready with their fingers on the trigger".
"We are not interested in an unjustified escalation but we have the right to defend our people," he later told reporters.
The latest violence comes at a difficult time for Hamas, which lost its most powerful backer in July, when Egypt's Islamist President Mohamed Mursi was ousted by the military. Relations with Egypt have deteriorated sharply since then.
"We urge Arab nations to support us so that we can get rid of the occupation and regain our land," Al-Hayya said.
The Palestinians want to establish a state in East Jerusalem, the West Bank and Gaza, territories captured by Israel in a 1967 war.
The Israel-Gaza frontier had been mostly peaceful for the past year following the Egyptian-brokered ceasefire.
However on Monday, Gaza militants fired two rockets at a southern Israeli coastal city and Israel bombed what it said were two concealed rocket launchers in northern Gaza. There were no casualties reported in those incidents.
A senior Israeli defense official said he did not expect the latest round of violence to lead to an escalation along the border. "As far as I can tell from Hamas, they are deeply deterred (by Israel) and I estimate that quiet will return," the official, Amos Gilad, told Israel Radio.
The Palestinian Authority, Hamas's Western-backed rivals who exercise limited rule in the Israeli-occupied West Bank, resumed peace talks with Israel in July.
But tension has also mounted in the West Bank, where eight Palestinians have been shot dead by Israeli soldiers and three Israelis have been killed since the negotiations began.
(Additional reporting by Noah Browning; Writing by Maayan Lubell; Editing by Crispian Balmer and Andrew Heavens)