Updated

The city of Kidal in the far north of Mali is on high alert after Tuareg rebels said Monday they have taken up strategic positions around the locality, setting the stage for the first aggression against a major city.

In just over two weeks, the rebels -- many who used to be part of Libyan leader Moammar Gadhafi's armed forces -- have attacked at least six towns in the north of the landlocked country. It's the first time the Tuaregs have picked up arms since the last rebellion ended in early 2009.

"We're surrounding the town, but we haven't cut it off completely," said Moussa Ag Acharatoumane, the Paris-based spokesman for the rebel group, the National Movement for the Liberation of the Azawad.

On Monday morning, security forces in Kidal prevented protests against the arrest Sunday of two female supporters of the rebels, a local official told The Associated Press. The official spoke on condition of anonymity for fear of reprisals.

"Given the repression by the Malian security forces in the town -- arresting our women -- we are considering what we should do next," Ag Acharatoumane said by telephone from Paris.

Heavy arms fire was heard around Kidal on Friday night and Saturday morning. Homeny Maiga, interim president of Kidal's Regional Assembly said the Malian Army had been firing rockets at rebel positions about 12 miles from the town.

"The army was firing rockets from a BM-21 launch vehicle, but it was a long way from town," Maiga said. "What's important now is that if the army and the rebels clash that it happens away from town so that civilians don't get involved," Maiga added.

If the rebels do attack Kidal, it would be the first regional capital they have attacked since they began their offensive just over two weeks ago. Since Jan. 17 the rebels have attacked towns across Mali's vast north in an area spread over hundreds of miles in the Sahara Desert.

The towns attacked so far have been small, some with a population of just a few thousand. The rebels say this has been part of their strategy and they have the capability to attack much bigger towns.

"Like all the other major towns in the north, Kidal is one of the towns we intend to take over," Ag Acharatoumane said. "Our strategy has been to attack smaller towns with major military bases first so later we don't have to worry about attacks coming from many directions."