TEL AVIV, Israel, June 30 (Reuters) - Tens of thousands of Israelis protested on Saturday against the dropping of a rape charge against the country's head of state who the attorney-general called a "serial sex offender".

President Moshe Katsav has submitted his resignation after admitting to committing sex crimes against women employees in a plea bargain that omitted an original charge of raping another woman who worked in his office.

Under the deal published on Thursday regarding a case that has brought unprecedented disgrace upon an Israeli president, Katsav admitted to committing indecent acts against one women and sexually harassing another woman employee.

If the court approves the bargain when charges are brought on Sunday, Katsav will also receive a suspended sentence instead of a jail term.

"It's a deal that stains us all, we should not agree to let this sully our society," Education Minister Yuli Tamir of the left-of-centre Labour party told the poster-waving crowd of more than 20,000 in Tel Aviv's Rabin Square.

The turnout was the highest in years for a women's rights protest in Israel where women have complained for years that authorities do little to counter sexual harassment at work.

Israel's Attorney-General Menachem Mazuz, who has been criticised over the deal, told Israel's Channel 2 television: "We have encountered a president who it turns out has behaved for years as a serial sex offender".

Mazuz described the woman in question as a "victim" of a relationship that deviated from proper employer-employee contacts, but that conflicting evidence led him to decide against bringing a rape charge against Katsav.

AlertNet news is provided by