TUNIS: An escalating confrontation between the Islamist regime in power in Tunisia since its 2011 revolution and a secular opposition party is to be taken to the International Criminal Court, the latter group said on Friday.

The opposition Nidaa Tounes (Call for Tunisia) party will lodge allegations of "crime against humanity" against several members and allies of the ruling Ennahda party "within days" in The Hague court, the party's lawyer, Abdessatar Messaoudi, told AFP.

The lawsuit will notably target Ennahda chief Rached Ghannouchi, Interior Minister Ali Larayedh and several regional governors and security officials, he said.

It will also name a militia called the "League for the Protection of the Revolution" that is suspected of beating to death a Nidaa Tounes representative in south Tunisia last October, Messaoudi said.

The lawyer said the opposition party will produce written and video evidence implicating Islamist leaders and militants in attacks against Nidaa Tounes.

The opposition party, founded in July and led by former premier Beji Caid Essebsi, is accused by Tunisia's ruling coalition of hosting former regime officials seeking to undermine the government.

Its supporters regularly clash with backers of the Ennahda movement.

Last month, hundreds of Ennahda supporters chanting "Out, you swine!" besieged a hotel on Tunisia's touristic Djerba island being used for a Nidaa Tounes meeting.

Since mid-2012, violent demonstrations and attacks by radical Islamist groups have increased across Tunisia, which is struggling to stabilise since the revolution that ousted former despot Zine El Abidine Ben Ali two years ago.