TUNIS: Tunisia's main Islamist Ennahda party will pick a hardliner to replace moderate outgoing Prime Minister Hamadi Jebali after he declined to head the next government, a party official said on Thursday.

Jebali, who is secretary-general of Ennahda, resigned on Tuesday after his plan for an apolitical technocrat cabinet to prepare for elections collapsed, largely because of opposition from within his own party and its leader, Rached Ghannouchi.

"Jebali declined to accept nomination (for next prime minister)," Ennahda said. "A new candidate will be presented to the president of the republic this week."

The assassination of opposition leader Chokri Belaid on Feb. 6 plunged Tunisia into its worst political crisis in the two years since a revolt toppled President Zine al-Abidine Ben Ali and inspired Arabs elsewhere to rebel against autocratic rulers.

The secular leftist's killing sent protesters flooding into the streets, exposing the deep rifts between Tunisia's empowered Islamists and their liberal and secular-minded opponents.

Jebali had proposed forming a technocrat cabinet to replace his Ennahda-led coalition, which included two secular parties, to spare the North African nation's nascent democracy and its struggling tourism-dependent economy from further strife.

But Ghannouchi blocked the moderate premier's plan and a senior Ennahda official told Reuters the next prime minister would come from the party's hardline wing, which opposes any role for politicians linked with the Ben Ali era.

The official listed outgoing Justice Minister Nourredine Bouheiri, Health Minister Abdellatif Mekki, Agriculture Minister Mohammed Ben Salem, Interior Minister Ali Larayedh and Transport Minister Abdelkarim Harouni as the possible nominees.

"Ennahda will hold a meeting tonight to choose a candidate. The next prime minister will be one of the names on this list," said the official, who asked not to be named.

In a televised address on Thursday, Jebali apologised to the Tunisian people for "failing and disappointing" them and urged them to unite to pull the country out of crisis.

"Tunisians must be patient during the coming months," he said. "Demands and sit-ins must stop until the revolution wins."

Ennahda won Tunisia's first free election in October 2011 and controls 89 seats in the 217-member National Constituent Assembly assigned the task of drafting a new constitution.

Tunisia's secular president, Moncef Marzouki, will ask the next prime minister to form his government within two weeks.

Ghannouchi has previously said it is vital that Islamists and secular parties share power now and in the future, and that his party was willing to compromise over control of important ministries such as foreign affairs, justice and interior.

Marzouki's secular Congress for the Republic party (CPR), which has 29 assembly seats and was part of Jebali's coalition, said on Thursday it was ready to join the next one.

"Our party will take part in the new government and will have an active role to play," the CPR's spokesman Hedi Ben Abbes said after a meeting with Marzouki.

Together, Ennahda and CPR would have 118 seats, wielding a majority in the assembly. It is not clear whether other secular parties would join such a coalition, particularly in the charged political atmosphere following Belaid's assassination.

Ennahda's own unity might also come under strain following the very public differences that have emerged between Ghannouchi and Jebali, who served as prime minister for 14 months.

Tunisia began a transition to democracy after Ben Ali's peaceful overthrow in January 2011, holding elections for the National Constituent Assembly and then forging a deal under which Ennahda agreed to share power with its secular rivals.

But disputes have delayed the constitution, and grievances over unemployment and poverty have led to frequent unrest.

Police seized a big weapons cache in Tunis on Wednesday night. "Dozens of Kalashnikov assault rifles, rocket-propelled grenades and explosives were seized in a home in Mnihla destrict," the Interior Ministry said.

Secular groups accuse Ennahda of being too soft on militants. In December, Interior Minister Ali Laryed said police had arrested 16 Islamists who had been accumulating arms with the aim of creating an Islamic state.

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

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".