BAMAKO, Mali — Protesters in the remote north Malian town of Kidal on Tuesday called for the release of dozens of rebels imprisoned in the distant capital, underscoring the tensions between the government and the largely separatist region before a presidential runoff election this weekend aimed at stabilizing the country.

The election is going ahead despite concerns over the lack of government control in Kidal, which is largely run by separatist Tuaregs, traditionally nomadic people who refer to the region as Azawad and have sought a nation of their own for decades.

The demonstrators are seeking the release of the 122 prisoners affiliated with the Tuareg separatist rebel group, the National Movement for the Liberation of the Azawad, or NMLA, said Rhissa Ag Abidine, who took part in the march.

Kidal, Mali's northernmost provincial capital, remained outside the scope of the national government for months following a Tuareg rebellion in early 2012. Discontent with the government's handling of that crisis later sparked a coup in March that unleashed political upheaval and forced hundreds of thousands to flee their homes across the country.

The Malian military only returned to Kidal last month and their presence there remains deeply unpopular. The Azawad flag flies across Kidal and rebels remain largely in control. Voter participation was dismally low in the first round presidential voting late last month, highlighting how many there do not pledge allegiance to the Malian government.

A spokesman for the National Movement for the Liberation of the Azawad, Moussa Ag Assard, said that in addition to freeing the rebels protesters also want the Malian army to leave Kidal.

Sunday's runoff is aimed at restoring constitutional rule in Mali, where an interim president has been leading since the coup's leader handed over power to a transitional government pending elections. More than $4 billion in aid pledged by donors is being held up until a legitimately elected government can be installed.