Israel Defense Forces soldiers shot dead two Palestinian men who approached the border fence separating Gaza from Israel overnight, Palestinian medical staff said.

The two brothers, in their forties, had walked close to an Israel-Gaza border terminal late on Friday night. Local residents said the men often scoured the area for cement and other building materials to sell. On Saturday morning, Palestinian ambulances evacuated their bodies from the scene.

An army statement said the two men appeared suspicious and were shot as they moved in darkness toward troops at the border fence, which is in an area off limits to Palestinians. The area is frequently used by militants trying to fire rockets at Israel. However, other Palestinians enter the danger zone to scavenge for building materials, to shoot birds, or to try and sneak into Israel to work.

"They approached our unit in a suspicious manner, crouched over," the spokeswoman said.

She had no immediate word on whether the soldiers were patrolling Israel's side of the fence or inside Gazan territory.

Israel has stepped up air strikes and military incursions since Islamist Hamas seized control of Gaza in June.

Also overnight in the Gaza Strip, a bomb went off close to a Hamas police building in Gaza. There were no injuries. There have been a series of bombs placed close to Hamas institutions in recent months, following its violent takeover of the Gaza Strip in mid-June from rival Palestinian group Fatah. There have been no claims of responsibility for the blasts, which have unnerved - rather than physically harmed - Hamas officials in Gaza. Hamas has blamed rival Fatah, which rules the West Bank, for the attacks.

On Saturday, Hamas' interior ministry in Gaza said they arrested a number of trouble makers they accused of blowing up a police jeep belonging to the militant group on Thursday.

Nobody was harmed in that explosion, which destroyed a standing car.

Hamas said the perpetrators were from the leadership of Fatah but provided no further details.

Hamas also said that five of its members have been arrested by security forces loyal to Palestinian Authority Chairman Mahmoud Abbas of Fatah in the West Bank over the past 24 hours.

According to the forces, the five had been detained for "shaking the order," and their detention had been part of a plan to restore security in some West Bank cities.

Security sources confirmed that some of the detainees were affiliated to the Hamas movement. However, Hamas said in a statement all of them were from its supporters.

Hamas condemned the detention as a bid to target the movement's growth in the West Bank. The arrest campaigns took place in Nablus and Jenin.

The crackdown against Hamas in the West Bank was launched in June in response to Hamas' capture of the Gaza Strip after fierce fighting with pro-Abbas security services.