Protesters crowded three streets leading to a square near Sanaa University, where students and pro-democracy demonstrators have been camped for more than a week.

"The people want the departure of Ali Abdullah Saleh," they chanted in unison. "The people want to overthrow the regime."

The protest got under way as Saleh called a press conference in Sanaa at which he accused Israel and the United States of fomenting anti-regime revolts rattling the Arab world.

"The events from Tunisia to Oman are a storm orchestrated from Tel Aviv and and under Washington's supervision," Saleh told reporters in Sanaa.

"What is taking place on Yemen's streets is just a copy-cat attempt, as Yemen is not Tunisia or Egypt and the Yemeni people are different," he said.

Saleh was referring to revolts that have hit the Arab world, leading to the ouster of Tunisia's veteran Zine El Abdine Ben Ali and Egypt's Hosni Mubarak.

Anger at authoritarian Arab regimes in the Middle East and North Africa is now raging from Algeria to Yemen and has spread to the previously unaffected Gulf States of Kuwait and Oman, both strategic Western allies.