Three leading Bahraini opposition activists, facing up to life in jail on charges of plotting to overthrow the monarchy, told their trial on Tuesday of how they were tortured in custody, their lawyers said.

The three - Shia clerics Abduljalil Muqdad and Saeed Mirza Mahroos, and the Sunni head of the secular Waed group, Ibrahim Sharif - all demanded that they be freed.

"They all complained of torture during detention," said a member of the defence team, requesting not to be identified.

Sharif gave a lengthy account of the torture he said he endured along with other detainees after he was arrested on March 17 last year, in the wake of a deadly crackdown on Shia-led pro-democracy protests.

"We were made to stand in a line, blindfolded. I had to go through a complete body search after they stripped us naked," he told the court, according to Radhi al-Mosawi, his deputy for political affairs at Waed, who tweeted Sharif's account on Twitter.