A car bomb has exploded in the northern Mali town of Kidal, killing seven people, reports say.
The attack is thought to have targeted a checkpoint manned by a Tuareg group which has come out in support of France's military intervention.
Islamist militants were driven out of Kidal and other strongholds but have continued to stage raids and bombings.
A senior UN humanitarian official has said hundreds of thousands of displaced Malians are too afraid to return home.
More than 430,000 people who fled the militant takeover of northern Mali last year did not feel confident enough to return to their homes despite the security situation improving, said John Ging, from the UN Office for the Co-ordination of Humanitarian Affairs.
Those who had stayed feared the conflict was not yet behind them, he added, amid reports of amputations and rape carried out by militants against women and children.
There were also fears among ethnic Tuaregs of reprisal attacks by Malian security forces, because Tuareg rebels took part in last year's rebellion before it was hijacked by Islamist militants, the UN official said.
The army has been accused of carrying out extra-judicial killings in areas where it has regained control.
Mr Ging said he had told Mali's government it should show it could protect civilians and secure cities in order for people to feel safe enough to come back.