Tunisia president Fouad Mebazaa calls election
Mr Mebazaa said voting for a council of representatives to rewrite the constitution would be held by 24 July.
He said a new interim government would run the country until then.
Mr Mebazaa said he would also continue in office, even though the current constitution limits caretaker office-holders to a 60-day term.
In a televised speech, he promised to stay in power, "contrary to what has been rumoured, until the elections are held, with the help and support of all".
Once elected, the constitutional council could either appoint a new government or ask the current executive to carry on until presidential or parliamentary elections are held, Reuters news agency said.
Tunisia has struggled to restore stability since mass protests ousted Mr Ben Ali on 14 January.
On Sunday, Prime Minister Mohammed Ghannouchi resigned from the interim government. Six other ministers have since stood down.
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