Zambia and the Democratic Republic of Congo are struggling to resolve a gridlock that has made the Kasumbalesa border impassable in the past week, hurting trade between the two countries and threatening diplomatic relations.
President Edgar Lungu said last week he would report DRC to the South Africa Development Community (SADC) over congestion at the Kasumbalesa border post in Chililabombwe district.
He blamed DRC for the congestion that stretched 67 kilometres on the Zambia side at the time. It had been reduced to about 50 kilometres on Monday evening.
President Lungu said the Democratic Republic of Congo should be compelled to open up its borders and clear trucks in large numbers.
Zambia's Lubumbashi consulate trade attaché Jane Muwowo-Kapema was quoted last month saying about Kwacha 7 million ($560,000) is collected monthly through Kasumbalesa border post where 500 trucks cross into the Democratic Republic of Congo (DRC) daily.
Truckers say more than 1,000 trucks were awaiting clearance on Monday evening. Authorities said they were clearing 420 trucks per day but were overwhelmed by the backlog that lasted seven days.
"We have been told that authorities are clearing 420 trucks per day, so there is improvement," SADC Truck Drivers President Stanely Muluka told Africa Review by telephone. That was, however, below the target of 700 trucks set by the two countries on Thursday last week.
The congestion started with a protest by truckers over clearance at Whiskey which means that between Kasumbalesa and Lubumbashi, a distance of 90 kilometres three toll points form a non-tariff barrier to trade.
In addition, the toll fees over the stretch are the highest in the region; reaching $900 for a round trip over a distance of the 420 kilometres to Kolwezi towards the Angola border.
Mr Muluka said truckers had lost revenue because their turnaround was affected.
"This is why we are urging the two governments to operationalize the other two border posts at Sakanya and Mokambo to ease the recurring congestion," he said.
The trucks were initially stuck between mining towns leading to the border as far as 67 kilometers starting from Chambishi, Kitwe, Chingola and Chililabombwe which connects to the Kasumbalesa border.
By Monday evening, the trucks were between Chingola town and Chililabombwe stretching 51 km to Kasumbalesa.
Zambia commerce, trade and industry permanent secretary Kayula Siame said a fast lane would be designated for trucks that have already been cleared to ease the traffic.
SADC Truck Drivers vice president Webby Puta said documentation that is done at Whiskey check point should be done at Kasumbalesa border post to decongest the long queues. Doing so, he said, would cut the distance to the off-loading bay by 90 kilometres.
The logistical nightmare at the border is hardly what the two countries need at this time.
After ascending to the DRC throne in January President Felix Tshisekedi has placed trade with neighbouring countries at the heart of his policies to revive the economy.
Zambia also sees strengthening of bilateral trade agreements with countries like DRC and Angola as well as trade centers at border points like Kipushi and Kasumbalesa as key to getting more exports across the Central Africa region.
In 2015, DRC consumed $575 million worth of Zambian products against $1.7 billion that it sold to its neighbour, placing the onus on Lusaka to address the trade deficit.
That could take a while because Zambia exports low value products - sugars and sugar confectionary, salt, sulphur, lime and cement, plastics and plastic articles; inorganic chemicals, precious metal compounds, milling products, starches, dairy products, eggs, honey, edible animal products, essential oils, soaps, lubricants and candles - to DRC.
In exchange it takes in metal concentrates for Copper and Cobalt which in February were banned by Kinshasha.
The country wants to refine more of the ores and streamline the means by which they are exported to curb illicit sales.
According to some reports, DRC exported slightly more than 130,000 tonnes of cobalt concentrates to China; equivalent to 13,000 tonnes of refined metal.
Cobalt prices have dropped by about a half from $60.1 per kilogramme in January to $30.4 per kilogramme mid-March. The ban on concentrate sales to Zambia was later rescinded but is subject to review after every six months.
Zambia's is DRC's biggest market after China ($3.26 billion) and third biggest seller after South Africa ($976) and China ($968), according to Fastmarkets data.