By Marco Trujillo
BAMAKO, Jan 17 (Reuters) - The first detachment of a West African regional force arrived in Mali on Thursday to reinforce French and Malian troops which have struggled to push back battle-hardened al Qaeda-linked rebels despite seven days of air strikes.
A contingent of around 100 Togolese troops, which arrived at Bamako international airport at around 1700 GMT, was due to be joined shortly afterwards by Nigerian forces already en route from Kaduna airport, in the north of the oil-producing state.
"Life is difficult for the people of northern Mali and the international community has the duty to help these people," said Togolese Lieutenant Colonel Mawoute Bayassim Gnamkoulamba. "That is why we think that it is necessary for us to protect Mali and we are proud today to fulfil that mission."
The rapid arrival of the U.N.-mandated African mission, which had not been due to deploy until September, was a boon for former colonial power France, which has warned that Islamist control of northern Mali -- a vast desert area twice the size of Texas -- posed a threat to the security of the West.
French troops, which had moved northwards from Bamako in an armoured column on Tuesday, pinned down some Islamist fighters in the small town of Diabaly but held back from launching a full-out assault as the Al Qaeda linked rebels had taken refuge in the homes of civilians, residents said.
French forces, now numbering some 1,400 soldiers, had begun ground operations on Wednesday against an Islamist coalition grouping al Qaeda's North African wing, AQIM, and the home-grown Ansar Dine and MUJWA militants.
Al Qaeda-linked militants who took dozens of foreigners hostage at a gas plant in Algeria said their action was in reprisal for Algiers' cooperation with the French attack on Islamists in northern Mali.