Customs officers in the eastern Democratic Republic of Congo have seized 375 kilogrammes of coltan, a precious mineral used in electronics, en route to Rwanda, an official said Saturday.

The seizure was made Thursday at the "Great Barrier" border crossing, the minister of mines in North Kivu province, Jean Ruyange, told AFP.

Officers stopped a jeep headed towards Gisenyi, across the border in Rwanda, because their suspicions were raised on seeing that the tyres were depressed even though no cargo was visible.

The following day "they noticed unusual work around the chassis, removed a metal plate and found a quantity of coltan, around 375 kilos (825 pounds)," Ruyange added.

The metallic ore is used in electronic devices such as mobile phones and laptops.

Ruyange said the driver was taken away for questioning and an investigation was under way to determine the origin of the ore and whether other shipments have already crossed the border.

The minister lamented "fraudsters (who) develop sinister ways to distract our units."

"We have had a lot of cases where they empty the tank, fill it with minerals and devise another fueling system."

The DR Cong has large reserves of oil, copper, gold and diamonds as well as coltan.

On several occasions, Kinshasa has accused Rwanda of supporting rebels of the March 23 Movement (M23), active in North Kivu since May 2012, and financed with the support of Congolese minerals. Kigali has always denied supporting the armed group.

In November 2011, Rwanda returned to the DR Congo more than 80 tonnes of cassiterite, coltan and wolframite that had been smuggled out of North Kivu.