Tunisian leaders began the search for a new prime minister yesterday to try to lead the North African nation out of its gravest political crisis since an uprising that inspired a wave of Arab revolts two years ago.

Rached Ghannouchi, the powerful head of the main Islamist Ennahda party, said the group had not named anyone to replace Prime Minister Hamadi Jebali, who resigned on Tuesday, but that he expected a new government to emerge this week.

“We need a coalition government with several political parties and technocrats,” Ghannouchi told reporters after talks with secular President Moncef Marzouki. Jebali quit after his plan for an apolitical technocrat cabinet to prepare for elections failed.

He had proposed it after the assassination of opposition leader Chokri Belaid on February 6 shocked Tunisia and widened Islamist-secular rifts.

Eventually it was Jebali’s own Ennahda party that scuppered the idea, extending a political impasse that has cast a shadow over Tunisia’s fledgling democracy and ailing economy.

Tunisia began a transition to democracy after the peaceful overthrow of President Zine al-Abidine Ben Ali in January 2011, electing a National Constituent Assembly to write a new constitution, and then forging a deal under which the moderate Ennahda agreed to share power with its secular rivals.

But disputes have delayed the constitution and the failure to tackle unemployment and poverty in a country that relies on tourism has dismayed many Tunisians and led to frequent unrest.

“Today I cannot send a message of reassurance to investors abroad because local investors in Tunisia are not reassured and the outlook is not entirely clear,” said Wided Bouchamaoui, president of Tunisia’s Chambers of Commerce and Industry.

Negotiations on a $1.78 billion loan from the International Monetary Fund cannot be concluded amid the latest uncertainty.

“Once a new government is named, we will inquire about its intentions/mandate. Once the political situation is clarified, we’ll assess how best to help Tunisia,” an IMF spokeswoman said.

Standard and Poor’s lowered its long-term foreign and local currency sovereign credit rating on Tunisia on Tuesday, citing “a risk that the political situation could deteriorate further amid a worsening fiscal, external and economic outlook”.