A mass exodus of tens of thousands of rats is expected to be unleashed in Japan as the world's biggest fish market is closed.

Tokyo's Tsukiji fish market is also a huge tourist magnet for its pre-dawn tuna auctions, some 900 businesses handling 480 kinds of seafood worth $14 million on a daily basis, as well as 270 types of fruits and vegetables.

But the huge market will close after 83 years and relocate over a period of five days to a brand-new facility in Toyosu, about 1.4 miles away (2.3 km) on the waterfront.

The moving operation is unprecedented and will see thousands of trucks and forklifts take part in the move, with tonnes of waste produced in the process, which is heaven for the furry rats that run all over the sewers of the city.

Fishmongers checking bluefin tuna before the new year's first auction at the Tsukiji fish market in Tokyo, which will close after 83 years

A rat near Tokyo's Tsukiji fish market, which is soon to close after 83 years, which is expected to unleash a mass exodus of tens of thousands of the rodents

Tsukiji fish market - the largest fish market in the world - has long been a tourist magnet for its pre-dawn tuna auctions

Tatsuo Yabe, a rat expert in the city, says the 23-hectare (57-acre) market near Tokyo's swanky Ginza district is home to 'not thousands but tens of thousands' of rats, attracted by fish off-cuts and the market's maze of sewers.

The authorities say the operation must be ruthless, thorough and silent, with a unit of highly trained Japanese agents to throw up a ring of steel to block any escape from the vast battleground.

Despite being vastly outnumbered, the unit's chief commander is confident of total victory against the enemy army - expected to scurry loose when the world-famous Tsukiji fish market closes next month.

A Tokyo government official who commands the Tsukiji anti-rat operation told AFP: 'They will likely start moving en masse once they notice something unusual... The week after the market closes on October 10 will be the major battle.

Some 900 businesses handle 480 kinds of seafood worth $14 million on a daily basis, as well as 270 types of fruits and vegetables at the famous market

Pest control workers will use hundreds of kilos of poison as part of their extermination plan

Tokyo officials - helped by veteran rat exterminators - will be blocking pipe and sewer exits and plugging holes in fences with corrugated sheets to tackle the rat problem

To prevent a mass exodus from Tsukiji, Tokyo officials - helped by veteran rat exterminators - are busy blocking pipe and sewer exits and plugging holes in fences with corrugated sheets.

Before the market is torn down, they will erect an impregnable 10ft (three-metre) steel wall around the site and slowly move in through the perimeter to 'corner and catch' the rodents, said the operation's commander, who asked not to be named.

In addition, they will instal 40,000 sticky sheets to catch rodents, along with traps and use 47st (300 kilograms) of rat poison.

Restaurants and bar managers in the area surrounding the market are on red alert for a possible influx of unwelcome rodent visitors.

A 56-year-old restaurant in Ginza, one of Tokyo's most fancy wining and dining districts just a stone's throw from the market, said: 'It's frightening. We heard rats scrabbling around when an old theatre building was torn down in this neighbourhood.

Moving the market unprecedented and will see thousands of trucks and forklifts take part, creating tonnes of waste in the process - unleashing rats from all over the sewers of the city

Japan's Tsukiji market will relocate over a period of five days to a brand-new facility in Toyosu, about 1.4 miles away (2.3 km) on the waterfront.

'Some of our neighbours are even feeding stray cats now. That is how defensive we are getting.'

The Ginza Street Association, which brings together local businesses, even created a special anti-rat taskforce last year.

Kazuya Takahashi from Tokyo exterminator GP Corporation said: 'We are calling on them [clients] to stay vigilant and not even keep the doors open because sewer rats may come right in once the moving starts.'

Hiroyasu Ito, a veteran fish trader as old as the Tsukiji market itself, has known Tsukiji since the days when buyers and sellers communicated via telegram.

Now chairman of the Seafood Wholesalers' Association, Ito is aware of the venerable market's issues.

The sparkling new Toyosu fish market features sensor-controlled doors and shutters and 'air curtains' blasted down from the ceiling that keep cool air inside and should keep dust and bugs and rats out

Fish brokers at the Tsukiji fish market ahead of its closure and relocation next month

He said: 'We have many problems. Birds fly in, and many things like rats come in and out freely.

'We've hardly had any food poisoning incidents in this market. We are proud of it.'

In recent decades, market players have made the utmost sanitary efforts, with special inspectors in white jackets checking on food safety every day.

The gigantic complex stands on reclaimed land nearly twice as large as Tsukiji, and it is fully air-conditioned and prepared to welcome its new tenants as part of the new Toyosu facility, equipped with state-of-art refrigeration.

Masataka Miyake, a Tokyo official preparing for the new facility, said: 'The biggest difference is that Toyosu is an enclosed market, so all buying and selling will be done in this building.

'I hope the new Toyosu brand will soon become a global household name.'

Originally planned in 2016, Tsukiji's relocation has been postponed several times, held up by revelations of heavy soil contamination at Toyosu, a former gas plant.

Doors and shutters at the new facility are sensor-controlled, and when they are open, air is blasted down from the ceiling -- like an invisible screen.

'The air curtain prevents the cool air from escaping outside,' added Miyake, as well as fending off unwanted intruders like dust and bugs - and rats.