Israeli troops arrested some 30 Palestinians in the West Bank overnight as they ramped up a massive search for three teenagers believed kidnapped by Hamas, the army said on Thursday.
The arrests raised the number of Palestinians detained to 280, of whom around three-quarters are members of the Islamist Hamas movement, a military statement said.
The three teenagers, two of them minors, disappeared from a popular hitchhiking spot near the sprawling southern West Bank Gush Etzion settlement bloc late on June 12, with Israel blaming Hamas.
It has launched a massive military operation to find them which also has the stated objective of crushing the Islamist movement's infrastructure in the West Bank.
"Approximately 30 suspects were detained overnight, counting a total of approximately 280 since the beginning of the operation. Out of the 280, 200 are Hamas operatives," the army said.
Soldiers searched around 100 locations and stormed 10 Hamas organisations, which the army said were used by the Islamists "to recruit, disseminate information and enable cash flow."
One of the sites targeted was the students' union at Bir Zeit University near Ramallah, the radio said.
But the widespread search and arrest operations sparked clashes overnight in the northern cities of Jenin and Nablus, the army said.
"During an operational activity in Jenin, a violent riot erupted during which Palestinians hurled IEDs (petrol bombs) and opened fire at the forces," it said.
"The forces responded with live fire, identifying hits," it added.
Clashes also broke out in Nablus where residents hurled an explosive device and rocks at the soldiers, prompting several arrests, the army said.
Overnight, Israeli war planes staged several raids on Gaza for the sixth night running after a day in which militants fired five rockets over the border, one of which damaged a house in southern Israel, the army said.
Again, there were no Israeli casualties.
The Israeli army said that in retaliation planes struck "terror sites" in northern and central Gaza.
Palestinian security sources said two Hamas training camps and a base used by its security forces had been hit.
Medics said three people were wounded.