Israel launched a new crackdown on the nearly 3-year-old Palestinian uprising Wednesday, imposing widespread curfews and announcing plans to halve the Arab work force from the occupied lands.

The curfews were to prevent demonstrations on the eve of the second anniversary of the Palestinian state declared by the Palestine Liberation Organization's parliament in exile on Nov. 15, 1988.The measures also came a day after two key pro-PLO Palestinian activists were ordered jailed for six months without trial for alleged involvement in inciting a wave of attacks against Israelis in the past month.

Israeli left-wingers protested the detentions of Radwan Abu Ayyash, 40, of Ramallah in the West Bank and Ziad Abu Ziad, 50, of Jerusalem.

Abu Ayyash heads the Arab Journalists' Union and Abu Ziad edits a Hebrew-language Palestinian weekly.

"The message of the Israeli government to the Palestinian leadership is clear: There is no point in being a moderate," said Dedi Zucker of the Citizens' Rights Movement.

Yossi Beilin of the left-of-center Labor Party warned that "the price is liable to be more unnecessary bloodshed."

The curfews in the occupied West Bank and Gaza Strip confined roughly 420,000 people indoors. Schools were also shut in the West Bank, keeping 300,000 Arab pupils away from classrooms.

Holiday celebrations were launched Tuesday night in Gaza and the West Bank in anticipation of the curfews. Activists set off firecrackers, draped outlawed Palestinian flags over electric wires and marched in the streets, Arab reports said.

Demonstrations persisted Wednesday before the curfews. In Gaza City's commercial district, school girls marched chanting pro-PLO and pro-Iraqi slogans, Arab reports said.

In Israel, authorities rounded up 1,350 Palestinians working without security permits, Army radio said. The sweep was part of a campaign launched last month in the wake of stabbing attacks in Israel.