Nigeria's President Olusegun Obasanjo has arrived in Senegal to mediate in its border feud with The Gambia.
In August, The Gambia increased prices on the ferry crossings over the River Gambia, which has led to a ferry boycott and a transport blockade.
The move has hit both economies hard and there is now an acute sugar shortage in southern Senegal.
People in Tambacounda town have to queue for hours to buy the precious commodity at hugely inflated prices.
Mr Obasanjo is set to meet his Senegalese and Gambian counterparts and the leader of Guinea-Bissau - indirectly affected by the crisis in the Senegalese capital, Dakar.
At a summit of the West African regional body Ecowas last month, Mr Obasanjo was mandated to help appease the tensions between the two neighbours.
The BBC's Alpha Jallow in Tambacounda says many basic food stuffs are in short supply, and the price of sugar - which is in high demand - has more than doubled from 20 US cents a kilogramme to 50 US cents.
"It is really a bad time for many households in Tambacounda," said juice seller Amanita Sow.
"Before the border problem, I used to buy a large quantity of sugar for my drinks business. Now not only is the price of sugar high, but it is very hard to come by."
At Tambacounda's main market customers queue for as long as four hours for a few kilogrammes, our correspondent says.
English-speaking The Gambia is a thin strip of land that cuts Francophone Senegal in two.
Senegalese transporters normally cross The Gambia in order to go between the north and south of their country.
When the Gambians doubled the price for the ferry the Senegalese were furious.
They boycotted The Gambia, preferring a long detour through the east of their country along bad roads.
The Senegalese boycott also hurt the Gambians for whom re-export is a major business.