* Chadian death toll rises to 25 after soldier dies of wounds
* African-led force mostly still in capital Bamako
* Kerry, in Paris, calls for African and U.N. action
By Ange Aboa
YAMOUSSOUKRO, Feb 27 (Reuters) - Chad's President Idriss Deby appealed to West African leaders on Wednesday to urgently speed up deployment of their forces to northern Mali where Chadian and French forces are locked in bitter fighting with al Qaeda-linked rebels.
Chad's contingent of some 2,400 troops has borne the brunt of battles with die-hard Islamists holed up in the Adrar des Ifoghas mountains after a six-week French-led campaign pushed the militants into the desolate region by the Algerian border.
France, which said Islamists' seizure of northern Mali last year was a threat to international security, hopes to start withdrawing its 4,000 troops from March but is waiting for the effective deployment of a U.N.-backed African mission, AFISMA.
"It's no longer time to talk, but time for action. The enemy is not waiting," Deby told his West African counterparts at a meeting of the ECOWAS bloc in Ivory Coast's capital Yamoussoukro. "We call on ECOWAS' joint staff to be quicker in sending troops to liberated areas to protect the population."
The Chadian death toll rose to 25 on Wednesday after a soldier died from his wounds in fierce fighting at the weekend in the Adrar des Ifoghas. Mali's army, expelled from the region in April by a Tuareg-led revolt subsequently hijacked by the Islamists, has yet to return to the country's far north.
"To my Malian military brothers, your place is at the front to defend the integrity of your territory," Deby said. "We are waiting for you on the edge of the Algerian border."
Some 70 percent of the 8,000 troops expected under the African-led International Support Mission to Mali (AFISMA) have already deployed to Mali, according to its own figures.
U.S. CALLS FOR U.N. ACTION
Regional heavyweight Nigeria has deployed some 1,200 soldiers in a bid to snuff out links between the alliance of Islamist groups in Mali, which includes al Qaeda's north African wing AQIM, and its home-grown Boko Haram militant movement.
But most African units remain in southern Mali, leaving French and Chadian forces responsible for security in the recaptured northern towns and offensive operations in the mountain and desert wilderness near the Algerian border.
An Islamist raid last week in Gao, the main city in northern Mali, was only repelled thanks to the intervention of French forces, despite the presence of Nigerien and Malian troops.
Despite this week's casualties, Chad remained committed to the fight and would increase troop numbers if needed, Deby said.
"The Chadian soldiers will stand alongside the African troops to completely wipe out these jihadis and by that I mean in the entire Sahel region," he told Reuters.
The ECOWAS summit, which continues on Thursday, is expected to back calls from France and the United States for the mission in Mali to receive a U.N. peacekeeping mandate.
"We should lean towards transforming AFISMA into a U.N. peacekeeping mission," said the summit's host and ECOWAS chairman, Ivorian President Alassane Ouattara.
A mounting wave of suicide bombings and Islamist raids on northern towns has highlighted the risk of the coalition becoming entangled in a bloody and long-lasting guerrilla war.
Seven people were killed in a suicide car bomb attack by suspected Islamist militants on Tuesday in the remote northern Malian town of Kidal.
Despite the worsening security situation, Mali's interim President Dioncounda Traore vowed his government would stick to a timetable to hold elections before the end of July, completing a transition to democracy after a military coup in March.
U.S. Secretary of State John Kerry, visiting Paris on Wednesday, voiced Washington's support for speedy elections as the only means of addressing Mali's long-term problems.
"Our shared goal now should be for African and U.N. entities to step up so that France has the ability to step back," Kerry said, flanked by his French counterpart Laurent Fabius.
In Bamako, AFISMA spokesman Yao Aldjoumani said that U.S. drones operating in northern Mali would help troops more easily track down Islamists holed up in an area the size of France. (Additional reporting by Abdoulaye Massalatchi in Niamey, Tiemoko Diallo in Bamako, Joe Brock in Abuja, and Alexandria Sage in Paris; Writing by Bate Felix and John Irish; Editing by Jon Hemming)