* Malian army reaches town of Hombori - military
* Islamists blow up bridge between Gao and Niger
* African troops prepare to join French-led offensive
* But African force needs airlift help, funds
French-backed government forces advanced into northern Mali towards the Islamist rebel stronghold of Gao on Friday, recapturing the town of Hombori and forcing al Qaeda-allied fighters to pull back under relentless French air strikes.
France sent troops and aircraft to its former colony two weeks ago to block a southward offensive by Islamists occupying Mali's north. French and Malian troops have been pushing forward on either side of the Niger River, securing several farming towns recaptured over the last week.
African Union leaders at a summit in Addis Ababa called on the United Nations to provide emergency logistics to allow a nearly 6,000-strong African ground force to deploy fully in Mali. The AU said this should be paid out of the UN budget.
Malian officials said government forces entered Hombori, about 160 km (100 miles) southwest of Gao, late on Thursday and said an offensive against Gao could take place in the next few days.
Gao, with the other Saharan desert towns of Timbuktu and Kidal, has been occupied since last year by an Islamist alliance that includes AQIM, the north African franchise of al Qaeda.
"Our troops supported by French forces entered Hombori yesterday evening without any combat. The Islamists had already deserted the town," a Malian military officer, who asked not to be named, told Reuters.
Mali's national radio said Hombori's inhabitants turned out to cheer the government soldiers.
South of Mopti, a Reuters reporter saw a large column of French armoured vehicles and supply trucks rolling northeast along the main road in the direction of Gao.
Western and African leaders say the U.N.-backed intervention in Mali is necessary to stop the country's north - a vast, lawless tract of desert and mountains that juts into the Sahara - from becoming a safe haven for radical Islamist jihadists seeking to launch international attacks.
The United States and the European Union are helping with the airlift of French troops and equipment to Mali but have ruled out sending any combat troops. An EU mission to help train the Malian army will start next month.
Britain said it was sending a Sentinel manned surveillance aircraft to assist the campaign against the insurgents.
ISLAMISTS BLOW ROAD BRIDGE
Malian officials said French air raids on Thursday hit rebel positions at Ansongo, 95 km (60 miles) south of Gao. This is on the road to neighbouring Niger, where Nigerien and Chadian forces are poised to join the fight against the Islamists.
But in a sign of Islamist rebel resistance, a Malian officer and residents living in the area south of Gao reported the militants had blown up a bridge at Tassiga, south of Ansongo, on the road following the Niger River down to Niger.
Two civilians were reported killed when their vehicle drove off the destroyed bridge, the same sources said.
French Rafale jets and Tiger helicopter gunships have been harrying the rebel fighters with air strikes on their vehicles, bases and stores.
The rebels have abandoned caches of munitions, including one, at Diabaly in central Mali, found to contain rockets for a Soviet-made BM-21 Grad multiple rocket launcher, witnesses said.
Despite the optimism now being shown by Malian military commanders, French officials have said their Islamist opponents appear well trained and well equipped, and are likely to resort to hit-and-run guerrilla warfare rather then committing to a conventional battle.
On Thursday, a split emerged in the Islamist militant coalition. One Tuareg leader of the Malian Ansar Dine group announced the creation of a new faction, said he wanted talks and rejected any alliance with AQIM.
France has 2,500 soldiers on the ground in Mali as part of its Operation Serval (Wildcat), while a total of 3,700 French armed forces members are involved in the whole operation, according to the French Defence Ministry.
Only around 1,200 soldiers of the African intervention force for Mali, known as AFISMA and to be mostly comprised of troops from neighbouring West African nations, have so far arrived in the country. Troops from Burkina Faso, Benin, Nigeria, Senegal, Togo, Niger and Chad are being deployed.
LOGISTICS AN OBSTACLE
Asked what was holding back the full deployment of the African force, the AU's peace and security commissioner, Ramtane Lamamra, told Reuters in Addis Ababa: "One word, logistics."
The AFISMA force needs airlift support, ammunition, telecoms equipment, field hospitals, food and water, he said. It also required training to operate in Mali's desert and arid mountains.
Later, Lamamra said the AU believed the UN should offer help. "We are facing an emergency situation and therefore we need to take these issues not in a business-as-usual manner, but to take exceptional measures in the UN Security Council."
UN-funded emergency help would be able to "sustain the first weeks or months of this operation". Lamamra also told journalists that the regional force needed more manpower.
"We are already at 6,000. We could go above that with more contributions from outside ECOWAS (the west African bloc)," he said. Countries have one week to pledge soldiers, reflecting the urgency over deploying the force, he said.
Asked whether the one-week cut-off was aimed at limiting the time French forces would spend in Mali, Lamamra said: "If that was the case, it would correspond with the concern expressed by the French government."
Chad and Niger are readying troops with desert fighting experience to cross the border from Niger towards Gao in a separate flanking offensive.
But Chadian Foreign Minister Moussa Faki told Reuters in Addis Ababa his country was having problems finding planes to ferry armoured troop vehicles to Niger for its contingent.
"We're waiting for assistance from the international community to help us deploy all of the equipment," he said.
A conference of donors to support the Mali intervention will be held in Addis Ababa, on Jan. 29 after the AU summit.
Lamamra said hundreds of millions of dollars would be sought to train, arm and deploy Malian and African troops. Earlier this week France put the targeted figure at about 340 million euros ($452 million) for a full year.
The European Union has earmarked 50 million euros to pay the salaries of the African ground troops, a French diplomatic source said. It was not clear what period this would cover.