GAO– French and Malian forces have repelled Islamist fighters who seized a key building in Gao, the main city in northern Mali, officials say.French Defence Minister Jean-Yves Le Drian said troops had finally driven out militants occupying the city hall. In further violence, al-Qaeda-linked rebels say they detonated a car bomb near a base housing French and Chadian troops in Kidal.At least one person is reported to have been killed.France intervened last month to help the Malian army oust Islamist militants who seized the north of Mali last year.Thousands of soldiers from African countries have also been deploying since then. Mr Le Drian told reporters in Brussels late on Thursday that Gao was back under government control after clashes earlier in the day. "Malian troops supported by French soldiers killed five jihadists and the situation is back to normal,” he said.It is not the first time a group of militants has infiltrated Gao since French troops recaptured it last month.Malian army spokesman Diaran Kone told the BBC that between 20 and 40 militants had entered the city on Wednesday night between 23:00 and midnight.After hours of explosions and gunfire, French and Malian forces then opened fire at the city hall with heavy machineguns, Reuters new agency reported.Gao’s mayor Sadou Harouna Diallo told the BBC he was hiding inside the city hall and could hear shooting outside at about midday.A spokesman for Mujao, the Islamist group which controlled Gao for nine months, said their fighters had entered Gao on Wednesday."Our troops have been ordered to attack. If the enemy is stronger, we’ll pull back only to return stronger, until we liberate Gao,” Abu Walid Sahraoui told AFP.He later said that Mujao had detonated a car bomb near a military base in Kidal.He told AFP the group had no difficulty getting into Kidal "to blow up a vehicle as planned”. "More explosions will happen across our territory,” he added.The BBC’s Maud Jullien in the capital, Bamako, said early reports suggested a black car drove up to a private residence about 500m (1,650ft) from a camp where French and Chadian soldiers are based and exploded, killing one person and injuring two others.Earlier this month, two suicide attacks in Gao - the first in Mali’s history - followed by fierce fighting in the city have led to fears it may be a long battle to bring security to the vast desert region.