* PM says his job not yet finished
* Regional neighbours want new government by end of month
By Adama Diarra
BAMAKO, July 29 (Reuters) - Mali's interim prime minister says he will stay on as head of government despite criticism he has failed to tackle the country's twin crises and just days before a deadline set by neighbouring states for the naming of a new team.
The West African nation, once seen as a rare stable democracy in a tumultuous region, has been split in two since a coup on March 22 paved the way for a military advance by northern separatists and al Qaeda-linked Islamists.
An interim government was formed under Prime Minister Cheick Modibo Diarra, a former NASA astrophysicist and political novice, to usher Mali to elections and reconquer the north. But, three months on, crippled by internal bickering, it has achieved little.
West Africa's ECOWAS bloc, which is pushing for the deployment of a 3,000-troop intervention force in Mali, earlier this month gave the country's political leaders until the end of July to form a new, more representative government.
But in an address broadcast on state television on Saturday night, Diarra said he would stay on to complete his job.
"I will not resign and I cannot resign," he said. "The Islamists did not take hold in the north on March 22 or April 17, but over the last 10 years. And it's not in three months that a transitional government will get the islamists out. We need time to organise ourselves."
While the coup was condemned abroad, the reaction in cotton- and gold-producing Mali was mixed, with some praising the removal of a political class they said was corrupt.
This pro-coup camp has broadly called for Diarra to remain and are opposed to a foreign military intervention. The prime minister's supporters were due to hold a rally on Sunday calling for him to stay on.
Interim President Dioncounda Traore, who spent weeks in France recovering from injuries he sustained in May when a pro-coup mob broke into his presidential palace and beat him up, returned to Mali on Friday.
Diarra stopped short of saying he would defy the president if asked to step down.
"I don't have time for polemic debate. My mission is to take back the north and organise elections," he said.
Ivory Coast President Alassane Ouattara, who holds ECOWAS's rotating presidency, told the French weekly Journal du Dimanche that the regional bloc was preparing to submit a new request for military invention in Mali to the U.N. Security Council.
According to ECOWAS planners, African forces would first restore stability in the capital of Bamako. After that, regional militaries will help revamp Mali's defeated military and look at helping it retake the north, however details remain sketchy. (Writing by Joe Bavier; Editing by Angus MacSwan)