Tunisia's prime minister appealed for calm on Saturday from pro- and anti-government groups planning rival mass protests this weekend.

The North African country is experiencing increased attacks by radical Islamist militants at a time when the secularist opposition is trying to oust a government led by the moderate Islamist party Ennahda.

"Tunisia is in need of national unity ... I call for calm so that the army and security forces can combat terrorism and not waste its efforts on protests," Prime Minister Ali Larayedh told a news conference.

Tunisian forces launched air and artillery strikes on Friday to try to rout militants who killed eight soldiers earlier this week in one of the deadliest attacks on security forces in decades.

A fledgling "Arab Spring" democracy, Tunisia now faces one of the worst crises since autocratic President Zine al-Abidine Ben Ali was toppled in 2011, the first in a wave of uprisings across the region.

Planned talks on the political and security crises on Saturday failed to produce results, as the main opposition groups declined to attend.

Instead, both the government and the opposition reiterated the positions they have held all week.

The two sides may be awaiting the outcome of this weekend's rival protests - both Ennahda and the opposition are calling for a show of force through mass demonstrations.

Supporters of Ennahda planned a "million man march" later on Saturday.

The opposition, which has been rallying daily, is planning a march on Sunday.

The opposition has been angered by the assassination of two of its senior members, and, emboldened by the army-backed ouster of its Egypt's Islamist president, wants to dissolve the government.