Four people have been arrested by police investigating alleged corruption involving ice cream sellers and lucrative sales spots.
It follows claims that bribes were paid to license traders in tourist hot spots around London's South Bank.
Homes in Thamesmead, south-east London, Kent, Chadwell Heath and South Ockendon in Essex, were raided on Thursday.
Four men, including a police officer and a Southwark Council official, are being held on suspicion of corruption.
Police are also looking into claims that some street traders may have been tipped off about council trading operations in advance.
The investigation follows allegations made in the summer.
The suspects are being held at separate police stations and their homes and offices are being searched.