The head of Venice’s port authority has called for work to start on a new channel in the city after the government approved plans to ban mass-market ships in the Venice lagoon.

The ban was introduced to reduce water traffic and stop ships weighing over 96,000 tonnes from sailing close to historic parts of the city, including St Mark’s Cathedral.

The government said it would look at rerouting big ships to a new channel known as the Contorta Sant’Angelo.

However, environmentalists have opposed the move, saying it will change the ecology of the lagoon and create surges of seawater that would damage the city’s buildings, The Telegraph UK reported.

Mr Costa dismissed concerns, claiming that the lagoon has been radically adjusted for centuries.

“The lagoon has always been adapted in order to defend the principal source of Venice’s power – its port,” he said.

“It is no longer a natural environment. The Venetian duke changed the course of four rivers in order to develop the port.”

He hopes the new channel will be operational within two years.

Meanwhile, Mr Costa has also revealed the city has plans for a new off-shore mega-port, which would be used to build the city’s trade business.

The new port could cost up to $3.8 billion (2.8 billion euros), with cost coming from both government and private investors.

Mr Costa said the ideal location for the new port would be beyond the islands that protect Venice from the open sea.