Israeli forces have entered the Palestinian refugee camp in Jenin, in search of militants who eluded capture during heavy fighting there last month.
Israeli troops, backed by tanks, went back into the West Bank town of Jenin and its refugee camp, sparking exchanges of gunfire with Palestinian residents.
But the army said its forces did not come under heavy fire and intend to withdraw as soon as wanted suspects are arrested.
There were no initial reports of casualties on either side.
During the operation, the soldiers surrounded the homes of members of the militant Islamic group Hamas, which has carried out suicide bombing missions.
Members of the military wing of Palestinian leader Yasser Arafat's Fatah faction, known as the Al-Aqsa Brigades, were also rounded up.
An Israeli Army spokeswoman described the raid as a pinpoint operation.
The operation returned Israeli soldiers to the scene of some of the fiercest fighting during a six-week Israeli military offensive against the West Bank. The offensive, which ended last week, was aimed at arresting suspected Palestinian terrorists and destroying their infrastructure.
Dozens of armed Palestinians and 23 Israeli soldiers were killed in battles in the Jenin refugee camp last month.
The Israeli Government blocked a planned U.N. inquiry into the conduct of soldiers, who carried out the operation.