Robbers impersonating policemen and driving a white VW Golf have robbed a man of R40 000 in Mitchell's Plein using a new modus operandi, police said on Tuesday.

The man who was robbed had just withdrawn cash from a bank in Mitchell's Plein when he spotted some money lying on the ground.

An unidentified man appeared and picked up the cash and offered to share it with the man who had just come out of the bank.

The two men then walked to a motor licensing testing centre on Katdoring Street where a Golf with three men pulled over next to them.

The driver of the vehicle introduced himself to the two men as a police detective and accused the man who had come from the bank of having stolen the cash and confiscated all the money he had on him.

After questioning the man, the men handed him a brown envelope containing papers instead of the man's R40 000 which he had withdrawn, before driving off.

A fraud case was opened and police are looking for the robbers described as being in their 40s.

Anyone with information could contact the Mitchells Plein police on 021 370 1706 or 079 313 9003.