TUNIS: Tunisian President Moncef Marzouki's secular party said on Monday that it would stay in the ruling coalition, but demanded the resignation of key Islamist ministers amid deepening political uncertainty.

"We have decided to freeze our decision to withdraw our ministers from the government, but if in one week we don't see any changes, we will quit the government," said Mohamed Abbou, Congress for the Republic (CPR) party chief.

The centre-left party is demanding the resignation of the justice and foreign ministers from Prime Minister Hamadi Jebali's Islamist party Ennahda, amid soaring political tensions after the killing of a leftist opposition leader.

"Two days ago we presented the resignation of our ministers, but we were contacted yesterday evening by the leaders of Ennahda, who replied favourably to all our demands," Abbou told a news conference.

He stressed that the CPR opposed the planned formation of a non-partisan government of technocrats, announced by Jebali in the wake of public outrage at the murder of Chokri Belaid, a leftist politician and fierce critic of the Islamists.

The killing triggered three days of violent protests in which one policeman was killed and 59 others wounded, according to the interior ministry.

"We are against a government of technocrats as it would allow for the return of figures from the former regime" of ousted president Zine El Abidine Ben Ali, Abbou said.

Ennahda, which heads the coalition government, has already rejected the plan, laying bare the divisions within his party, in which he is considered a moderate, and fuelling a political crisis.

Hundreds of Tunisians Monday protested outside the national assembly demanding the government's resignation, among them Belaid's wife Besma Khalfaoui.

"This government must resign today, not tomorrow or the day after tomorrow. When a government fails, it must take responsibility," she told AFP, while those around her shouted: "resign, resign," and "the people want the regime to fall."

Jebali, who has set a target date of the middle of this week to form a transitional, non-partisan government, stuck to his guns on Monday, saying he had "no other choice," and renewing his threat to quit if he failed to do achieve his goal.

"The situation is... urgent, there is a danger of violence. I am responsible for the government, I cannot wait," the premier told French newspaper Le Monde.

He said the new government's priorities would include development, job creation and reducing high living costs, with anger over poor living standards continuing to drive social unrest in Tunisia two years after the revolution.

Despite opposing Jebali's plan, the CPR's Abbou described it as "historic and positive, seeing how he went beyond his party," but he insisted on the need to "respect the legality" of the elected government.

In contrast, the third party in the coalition government, Ettakatol, threw its support behind the shake-up, with Finance Minister Elyes Fakhfakh saying it was necessary to "ensure the best possible success of this initiative."

Ennahda hardliners are refusing to give up the key portfolios, and have warned that they will take to the streets of the capital, as they did in on Saturday, to insist on the party's right to govern following its October 2011 election triumph.

Since Wednesday, Tunisia has seen street clashes between police and opposition supporters and attacks on Ennahda offices, while Belaid's funeral on Friday turned into a massive anti-Islamist rally, believed to be the largest since the revolution.

The killing has enflamed tensions between liberals and Islamists, simmering for months over the future direction of the once proudly secular Muslim nation, and stoked by a controversial pro-Ennahda militia blamed for attacks on secular opposition groups.