Mohamed Bakhti, a prominent figure in Tunisia's Salafist movement, died on Saturday, nearly two months after launching a hunger strike following his arrest for an attack on the US embassy, his lawyer said.

"He died in hospital at around 2:00 am overnight," said Abdelbasset Ben Mbarek, noting that his death came after another member of the Islamist movement, Bechir Gholli, died on Thursday also after refusing food for nearly two months.

The lawyer had warned that Bakhti, who was suffering from a brain haemmorrhage, was in critical condition for several days.

Bakhti and Gholli started their hunger strike in late September, days after their arrest for a September 14 attack on the US embassy by a crowd of Islamists during which four of the assailants were killed in clashes with security forces.

They insisted they were innocent and protested over the conditions of detention, while the Salafist movement charged it was being victimised by the authorities.

Bakhti was considered a senior figure in the jihadist movement and close to Abu Iyad, the alleged organiser of the embassy attack which is on the run.

He was jailed for 12 years in 2007 for bloody clashes between the army and Islamists in Soliman, near Tunis, under Zine El Abidine Ben Ali's regime but released under an amnesty declared after the 2011 revolution.

In the attack on the US mission, several hundred protesters, angry over an anti-Islam film made in the United States, stormed the sprawling embassy compound in a suburb of Tunis.