A first plenary session of Tunisia's elected Assembly since the launch of all-party crisis talks was delayed on Tuesday with parliamentary groups reportedly at odds over an electoral commission.

The deputies were to have met at 9:30 am (0830 GMT) to examine amendments to a law setting up the commission but the session was postponed until 1430 GMT, the Constituent National Assembly said.

Al-Bawsala, an independent NGO which covers Assembly affairs, said the delay was caused by "disagreements on the law ... between different parliamentary groups."

Under a timetable agreed by Tunisia's ruling Islamists and the opposition, the electoral commission has to be formed by Saturday.

A "national dialogue" was launched last Friday and the government led by moderate Islamist movement Ennahda is to be replaced as part of a roadmap aimed at breaking a months-long political stalemate.

A new prime minister will have two weeks to form a government of independents under the timetable for the talks.

Incumbent Prime Minister Ali Larayedh has pledged to step down so long as the timetable is respected. The Assembly has until the end of November to also draw up a new constitution and an electoral law.

Tunisia's political crisis erupted in July, when the assassination of an opposition leader, Mohammed Brahmi, by suspected jihadists triggered calls for the resignation of Larayedh's government.