Tunisia's new coalition government will be unveiled on Friday, premier-designate Ali Larayedh said, after a deal was reached in last-minute talks aimed at ending the country's political crisis.

"After marathon negotiations, we have reached an agreement on the government... we are going to give it the final touch tomorrow morning" before presenting the plan to the president, Larayedh said late Thursday.

Larayedh, the outgoing interior minister, added that the parties had reached an agreement on a political program for the new government that would guide its priorities, policies and commitments, according to President Moncef Marzouki's office.

The president's office had earlier said that the new cabinet lineup would be unveiled by Larayedh late on Thursday. No reason was given for the delay.

Larayedh was tapped on February 22 to head a new government, with a two-week deadline to present his team and government programme to Marzouki. The deadline runs out at midnight on Friday.

The hopes of Larayedh and his ruling Islamist party Ennahda to form a broadly based coalition appeared compromised after three political parties that had been asked to join earlier announced they were pulling out of the talks.

Consequently, only Ennahda and its secular allies in the previous government -- Marzouki's Congress for the Republic and Ettakatol -- actually took part in discussions about the composition of a new cabinet and a proposed government programme.

Ennahda, to which Larayedh also belongs, has made a key concession in accepting that key ministries such as interior and justice be entrusted to independent candidates.

Tunisia has been in a political crisis since the February assassination of leftist politician Chokri Belaid, a vocal critic of the Islamist-led government.

Belaid's murder led to the resignation of prime minister Hamadi Jebali after he failed to forge a non-partisan government of technocrats when his ruling Ennahda party refused to support his efforts.

If a cabinet is not named by Friday night, Marzouki must choose another politician to form a government.

"Failure doesn't scare me because what is asked of me is to have a clear conscience and make the maximum effort. Everyone will have to take responsibility for the result," Larayedh told Mosaique FM radio.

After the president reviews the plan, the new government lineup must be approved by the National Constituent Assembly within three days.

In addition to the political upheaval, violence and attacks blamed on the ultra-conservative Muslim Salafist movement have rocked Tunisia in recent months.

There have also been protests sparked by growing unemployment and poverty -- the key problems that triggered the 2011 revolution.