VENICE — Venice became the world's first city to introduce a payment system for tourists on Thursday in an effort to thin the crowds that throng its canals, but the fee drew protests from some residents saying they did not want to live in a theme park.

Signs were set up outside the train station and near an entry footbridge warning visitors they had to pay the new 5 euro ($5.40) charge before diving into Venice's narrow alleyways.

Simone Venturini, the city's top tourism official, said the measure would help Venice find "a new balance" between residents and day-trippers, but hundreds of local protesters saw things differently.

"We are against this measure because it will do nothing to stop overtourism," resident Cristina Romieri said. "Moreover, it is such a complex regulation with so many exceptions that it will also be difficult to enforce it."

Giovanni Andrea Martini, a member of an opposition group in the Town Hall who joined the residents' protests, called it "a sad day because Venice is becoming a museum, a theme park".

Holding banners reading "No to ticket for Vene-Land" and chanting"Here we live and here we stay", a few hundred people peacefully marched through a main square to express their opposition.

Venice Mayor Luigi Brugnaro said 15,700 people bought tickets on Thursday, the first of 29 days through July of the plan's test phase when people must buy a ticket if they want to access the lagoon city from 8:30 am to 4:30 pm.

Although there are no turnstiles at the city gateways, inspectors will be making random checks and issuing fines of between 50 and 300 euros to anyone who has failed to register, but officials said they are seeking to persuade rather than punish.

The initiative is one of a series of measures in place across Italy to manage tourist flows.

Some 20 million people visited Venice last year, a city official said, with roughly half of them staying overnight in hotels or holiday lets, an influx which dwarfs the resident population of about 49,000.

People with hotel reservations and visitors aged under 14 do not need to pay the entry fee, but still need to register beforehand. Residents, students and workers are exempt.

UNESCO threatened last year to put Venice on its list of heritage in danger, citing mass tourism as well as rising water levels in its lagoon, which are attributed to climate change.

Venice escaped the ignominy only after local authorities agreed on the new ticketing system.

Agencies Via Xinhua