TUNIS (AFP) - Ruling Islamist movement Ennahda and the opposition Nidaa Tounes said on Sunday they have held secret talks in Europe to try to find a way out of Tunisia's political crisis.

Nidaa Tounes leader, ex-premier Beji Caid Essebsi, a sworn enemy of the Islamists, met Ennahda chief Rached Ghannouchi while on a European tour last week, his centre-right party said in a statement.

Ghannouchi himself wrote on Facebook that he had held "positive and frank" talks with Essebsi on Thursday, but he too did not elaborate.

The encounter took place in Paris, according to Tunisian media reports.

Ennahda has been holding internal talks since Saturday to examine "initiatives" to resolve the crisis which broke out with the July 25 assassination of opposition politician Mohamed Brahmi.

A second round of negotiations with the powerful UGTT trade union organisation aimed at striking a compromise is scheduled for Monday.

The moderate Islamist movement which heads Tunisia's ruling coalition has offered negotiations with the opposition to bring in other parties and form a government of national unity, but it rejects opposition calls to step down.

Ennahda's supporters are determined that after long years of repression under president Zine El Abidine Ben Ali, who was ousted in Tunisia's 2011 revolution, the party not be denied a share of power.

Last Tuesday, the two sides held rival rallies, highlighting the deep divisions over the balance to be struck between secularism and democracy following the revolution.

Ennahda insists it has the right to lead the government after emerging as the largest party in an October 2011 election for a constituent assembly.

The mainly secular opposition accuses Ennahda of failing to take strong enough action against hardline Islamists accused of Brahmi's murder and the slaying in February of another prominent secular politician, Chokri Belaid.