Taoufiq Bouachrine, known for his editorials criticising officials in the North African country and who had previous run-ins with the authorities, was arrested on Friday at his newspaper, Akhbar al-Yaoum.
A colleague said around 20 plain-clothed policemen raided the newspaper and detained him.
But defence attorney Mohamed Ziane dismissed the accusations against his client, suggesting his arrest was politically motivated.
“His arrest was spectacular, and this proves it is not a sex case, otherwise he would have been summoned to confront his accusers,” Ziane said.
Initially the authorities declined to explain why Bouachrine had been arrested, but on Saturday the prosecutor issued a statement saying he was detained following “complaints of sexual assault”.
The journalist, seen as close to the ruling Islamist Justice and Development Party, has had a tense relationship with the authorities.
A month ago a court ordered him to pay the equivalent of $50,000 (40,000 euros) to two government ministers who had accused him of defamation.
In 2009, Bouachrine and Akhbar al-Yaoum cartoonist Khalid Gueddar were each handed four-year suspended jail sentences following two separate trials over a cartoon deemed offensive to Morocco’s royal family.
The pair were also ordered to pay heavy fines and damages, and the paper was temporarily shut down.
In June 2010, Bouachrine was sentenced to six months for fraud around a property deal.
Akhbar al-Yaoum is one of the most influential Arabic-language newspapers in Morocco.
Media watchdog Reporters Without Borders (RSF) ranked Morocco 133rd out of 180 countries in its World Press Freedom Index last year.
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