* Some allies appeal for delay to Mali military action
* Ivorian PM says delay would increase cost, spread militancy
* Mali risks destabilising entire region, PM says
By Daniel Flynn
PARIS, Dec 6 (Reuters) - West African states must deploy a military force in north Mali quickly or it will become increasingly difficult and costly to oust Islamist groups there, Ivory Coast Prime Minister Daniel Kablan Duncan said in an interview.
Duncan, a former foreign minister, said that calls from Washington and elsewhere for a delay in introducing a force of 3,300 African troops were misguided as this would increase the risk of militant attacks in West Africa and beyond.
The U.N. Security Council tasked West African states in October with preparing a plan for military intervention to wrest control of north Mali from Islamist groups, which seized control of the vast desert region following a military coup in April.
In recent weeks, however, Washington has pressed for political negotiations and said any military action would require time. The head of U.N. peacekeeping, Herve Ladsous, said on Wednesday no intervention could take place before September due to weather conditions and the need to train Malian troops and pursue peace talks.
"Some allies are asking if we need to intervene right now. Our position is yes, we do, because the longer we wait the more these groups will put down roots. It will be more difficult afterwards and more expensive," Duncan told Reuters in Paris, where he attended a conference with international donors.
Duncan said al Qaeda militants from Afghanistan and Pakistan had travelled to Mali to reinforce the group's north African wing, al Qaeda in the Islamic Maghreb (AQIM), one of several groups controlling northern Mali.
Delaying intervention would make it much harder to dislodge these foreign fighters, who were training militants from across the region, particularly members of the Nigerian Islamist sect Boko Haram, he said.
"There is a destabilisation of the region taking place in Mali," Duncan said. "We have to get rid of these groups. Nor can we tolerate the traffic of drugs and the taking of hostages."
Seven French nationals are being held in the Sahel region, which has also increasingly become a haven for international organised crime groups. France is the most outspoken Western advocate of military intervention.
Duncan welcomed negotiations with two rebel groups which opened on Tuesday in neighbouring Burkina Faso, while maintaining that military intervention was unavoidable.
The Tuareg separatist MNLA, which launched the northern uprising, and Ansar Dine, a local Islamist group which quickly usurped control of the movement, have agreed to work towards a negotiated solution with Malian officials.
Duncan said the threat of military force played an important role in bringing these groups to the negotiating table and keeping them there.
"These groups only said they were ready to negotiate when African states showed they were ready to intervene. If we don't continue to pressure them, tomorrow they will simply walk away."
Ivory Coast has its own security concerns following a brief but brutal civil war sparked by former President Laurent Gbagbo's refusal to recognise Alassane Ouattara's 2010 election victory. Ouattara was finally sworn in as president in May 2011 with French military backing.
The United Nations has postponed until next year downsizing its 11,000-strong peacekeeping mission to Ivory Coast, deployed in the wake of a 2002-2003 conflict, because of unrest near the country's eastern and western borders and in Abidjan.
Duncan said the government was stepping up efforts to reintegrate ex-combatants and working with neighbouring Liberia and Ghana to prevent exiled pro-Gbagbo groups from crossing the border to carry out attacks.
He said Ivory Coast had won funding from donors at this week's Paris conference for a $250 million programme to decommission arms and reinsert ex-combatants into society. The conference produced total pledges of $8.6 billion, twice the level the government sought.
"No African state has ever bounced back so fast from a crisis," he said. "There will be a stabilisation in Ivory Coast." (Editing by Sonya Hepinstall)