More than 2,400 people were caught allegedly watching television without a licence in Bristol during the first six months of 2010.
A TV Licensing spokesman said across the United Kingdom almost 209,000 people were caught in the same period.
"The vast majority of people in Bristol do pay their licence fee... we have to be firm with those who attempt to get away without paying," he said.
A colour TV licence costs £145.50 and can be paid for in instalments.
"We take TV licence evasion very seriously and, while we give people every opportunity to pay, we will not hesitate to prosecute if people continue to break the law.
"Anyone watching TV illegally risks prosecution and a fine of up to £1,000," the TV Licensing spokesman added.
During the same time period 356 people were also caught in Weston-super-Mare and 175 in Bath.