GAZA CITY, Gaza Strip - A senior Gaza Hamas official warned Tuesday that his Islamic militant group could overrun the West Bank, just as it took over Gaza, if provoked by its rivals in Fatah.

The official, Sami Abu Zuhri, spoke as tensions between the two groups remained high following a bombing that killed five Hamas members in Gaza and a Hamas sweep that ended with 11 dead and dozens wounded, most of them from Fatah.

Abu Zuhri, told The Associated Press that Fatah should expect "an uprising" against them if they continued a crackdown against Hamas there.

A West Bank Fatah official responded that Hamas was issuing empty threats. After Hamas expelled Fatah forces from Gaza in June 2007, Palestinian President Mahmoud Abbas of Fatah set up a government in the West Bank. Israel withdrew from Gaza in 2005 but maintains a large military presence and overall security control in the West Bank.

Abu Zuhri's interview with the AP reflected Hamas' increasingly tough stance toward Fatah, after it routed the Fatah-linked Hilles clan in Gaza City over the weekend.

The Hamas sweep underscored Hamas' tight control in the coastal territory.

Dozens of the clansmen fled to the West Bank through Israel, running over hills and dodging gunfire to escape Hamas fighters.

As the conflict has intensified, Hamas in Gaza and Fatah in the West Bank have rounded up dozens of political opponents, amid growing reports of beatings and mistreatment of detainees by both sides.

Abu Zuhri said the crackdown on Hamas loyalists would not break the movement. Instead it would bring "the opposite result."

"It will lead to what will appear like an uprising against the Palestinian Authority in the West Bank," he said.

Abu Zuhri said his movement was not actively planning for a military takeover, but it was an option.

"If arrests continue, they will lead to unplanned-for responses, whether from resistance fighters or the people," he said.

Fahmi Zaarir, a spokesman for Fatah in the West Bank dismissed the Hamas threats. "If they can do anything, let them do it. We are not afraid," he said.