GAZA CITY, Gaza Strip ? President Mahmoud Abbas on Friday vetoed Hamas’ plan to set up a security force of 4,000 militants, but Hamas insisted it would go ahead, deepening the tensest clash yet between the Islamic group and the moderate Palestinian leader.

Hamas, which ousted Abbas’ Fatah Party from power in January parliamentary elections, had spoken in the past of incorporating militants into the Fatah-dominated Palestinian security forces.

But the concept of a shadow security force headed by the No. 2 fugitive on Israel’s wanted list appeared to go too far for Abbas, who favors talks with Israel and is trying to keep the West from shunning the Palestinians over Hamas’ violently anti-Israel ideology.

The new force, to be based in chaotic Gaza, is to have about 4,000 members – nearly one-fourth the size of the 18,000-member armed security contingent in the coastal strip.

Egypt, meanwhile, invited interim Israeli Prime Minister Ehud Olmert for an official visit even before he has put together his government, signaling it is eager to do business with a man keen to draw Israel’s final borders with the Palestinians within the next four years.

Egyptian President Hosni Mubarak extended the invitation in a telephone call to Olmert, and a date for the visit is to be set next week, aides to the Israeli leader said. Israeli and Egyptian leaders have not met since February 2005.

Egypt’s MENA news agency reported the phone call, but did not mention any invitation.