TEL AVIV, Dec 30 (Reuters) - An Israeli court found former President Moshe Katsav guilty of rape and other sexual offenses on Thursday, convictions of unprecedented gravity for a head of the Jewish state.

Katsav's testimony was riddled with lies, the three-judge panel said in its ruling. When a woman says no, she means no.

Katsav, president from 2000 to 2007, had denied the charges of twice raping one former aide and of forcibly molesting or sexually harassing two others. He had also been indicted for witness tampering and obstruction of justice.

The 65-year-old Katsav had no comment for reporters as he left Tel Aviv District Court, ashen-faced and flanked by lawyers and bodyguards. He may appeal to the Supreme Court to contest the unanimous verdict, and what could be a lengthy jail term.

Though the scandal had forced Katsav's early retirement in disgrace, it had no impact on Israeli government functions, as the presidency is largely ceremonial.

But the allegations against the Iranian-born leader, whose rise from the slums once served as a shining example for disadvantaged Jewish immigrants from the Middle East and North Africa, stirred deep emotions in Israel, where the head of state is supposed to be a beacon of morality and national unity.

Katsav had cast himself as the victim of extortion and an ethnically-motivated witch hunt, and had vowed to clear his name.

The verdict was dubbed an earthquake by one Israeli newspaper and welcomed by women's groups that have long complained of lax attitudes to sexual harassment in workplaces.

Out of concern for the complainants' privacy, much of the trial had taken place behind closed doors. Some commentators predict Katsav, should he appeal, will argue that the Tel Aviv District Court proceedings were not transparent enough.

The court did not immediately publish a date for Katsav's sentencing. Rape carries a minimum prison sentence of four years and a maximum of 16 years, Israel Radio legal analyst Moshe Negbi told Reuters. Any sentences handed down for the lesser charges would likely be served concurrently, Negbi said.

Katsav immigrated with his family to Israel in 1951. At age 24 he became the country's youngest mayor and went on to hold a number of cabinet posts as a member of the rightist Likud party.

Parliament elected him president in 2000 in an upset victory over Shimon Peres, Israel's Nobel Peace Prize-winning elder statesman. Peres succeeded Katsav as president.

It's not pleasant to see a former president tried for serious crimes like this, Negbi said. But on the other hand, I think every citizen should be proud that we live in a country where the number one citizen is subject to the law.

(Writing by Rami Amichai and Dan Williams; Editing by Peter Graff)