BAMAKO: Malian soldiers fired warning shots at Islamist fighters overnight amid fears they plan to advance on the government-controlled south of the country, a military source said Tuesday.

The fighters retreated after the shots were fired at Kona near the town of Mopti, which lies about 650 kilometres (400 miles) northeast of the capital Bamako, the source told AFP.

"The Malian army on Monday and during the night fired warning shots at the enemy, who pulled back," the source said.

Mopti is the last major town south of a vast desert swathe of the west African country which fell into the hands of armed Islamist groups and Tuareg rebels after a coup that rocked Bamako last March.

Former colonial power France called on Islamist groups to halt any southern advance.

"I can only express France’s strong worries regarding these movements and our call that these groups stops these movements to the south and resume negotiations," foreign ministry spokesman Philippe Lalliot said.

The incident was the first time Malian soldiers and rebel forces have come so close to a direct confrontation since the Islamist movements seized terrain and sidelined their Tuareg allies.

A Malian government official said defence ministry staff would meet Tuesday.

Security sources and witnesses have said that three Islamist rebel groups had set up a military base in Bambara Maoude, a town near Timbuktu.

These movements control Timbuktu, Kidal and Gao, all three of the regional administrative centres in northern Mali.

The rebel groups -- the Al-Qaeda-linked Ansar Dine, the Movement for Oneness and Jihad in West Africa (MUJAO) and Al-Qaeda in the Islamic Maghreb (AQIM) -- have been joined by members of Boko Haram, an Islamist extremist movement blamed for thousands of deaths in nearby Nigeria, security sources said.

One regional security source said he was "deeply worried" and suspected the Islamists planned to head southwards into government-held territory.

Ansar Dine and another armed group in the north, the ethnic Tuareg Azawad National Liberation Movement (MNLA), are homegrown movements, while the other two movements have infiltrated the vast territory.

Ansar Dine, which insists on strict observance of sharia law, said Thursday that it had revoked a pledge to end hostilities. The movement's chief, Iyad Ag Ghaly, accused the government of not being ready for talks, but he did not close the door to negotiations.

The MNLA and Ansar Dine attended their first talks with the government on December 4, under pressure from Burkina Faso and Algeria, two countries acting as mediators. Late last year, Ansar Dine said it renounced imposing sharia throughout Mali, but would do so in its zones of influence.

The regional Economic Community of West African States (ECOWAS) has 3,300 troops on standby for a mission to reclaim northern Mali that received the approval of the UN Security Council on December 20.

However, the United Nations has also held out for negotiations between armed groups and the Bamako government, while some Western military sources have cast doubt on the ability of the regional force to fight a guerrilla war in unfamiliar desert terrain.

Moreover in November, UN special representative for the Sahel Romano Prodi said that no intervention could take place before September 2013, to allow time for the preparation of the African force.

Mali's interim President Dioncounda Traore said in his New Year's message to the nation that the authorities were preparing for "war against the terrorists" without waiting for months and with the Malian army in the front line.

Also Tuesday, a senior UN official expressed concern over the plight of women in particular in northern Mali.

"We are really concerned about the women's situation in the north, where women are victims of sexual violence and also children," said former Chilean president Michelle Bachelet, who heads the United Nations Entity for Gender Equality and the Empowerment of Women.

"We are interested in showing what we can do to protect those women from those kind of dangers," she added.

Under their strict interpretation of sharia law, Islamists have introduced many tough measures including some that target women, such as the mandatory wearing of a veil.