Tunisia's largest labour organisation, the UGTT, said it would hold a general strike on Friday to protest against the assassination of opposition figure Mohamed Brahmi, officials said

Brahmi, a leading opposition figure and critic of Tunisia's ruling Islamists, was shot dead by unknown gunmen outside his home near the capital Tunis on Thursday.

"The executive office of the UGTT decided to go on general strike ... it will be a political strike in defence of Tunisia and to protest at this new political assassination," Sami Tahri, a UGTT spokesman, said.

A general strike was held on Feb. 8, two days after the assassination of the secular opposition figure Chokri Belaid.

Meanwhile, UN human rights chief Navi Pillay on Thursday condemned the killing of Tunisian opposition politician Mohamed Brahmi, demanding an investigation into his slaying, AFP reported.

"I am shocked and deeply saddened by the news of Mr. Brahmi's assassination. I call upon the authorities to immediately launch a prompt and transparent investigation to ensure that the people who carried out this crime are held accountable," Pillay said in a statement.