* Seoul braces for 260,000 fans to watch BTS perform

* Seoul police shut streets, put up fences and metal

detectors

* Concert marks BTS' comeback after more than three years

* Netflix ( NFLX ) to stream concert live, BTS to start world tour

(Adds concert media coverage relaxation, in paragraph 11)

By Joyce Lee

SEOUL, March 21 (Reuters) - South Korea shut down the

heart of Seoul on Saturday for a comeback concert by Kpop

supergroup BTS, as authorities prepare for an estimated 260,000

fans to flood the city's streets and millions more to watch the

show live on Netflix ( NFLX ).

The one-hour-long concert, set to be held in the capital's

historic Gwanghwamun Square, marks the ​release of the

seven-member group's first new album in more than three ​years,

and the start of a global tour in April.

BTS made their debut in 2013 and have since gone on to global

superstardom, becoming the most streamed Kpop artist globally on

Spotify ( SPOT ) with its members invited to the White House and

partnering with the UN General Assembly. In 2022, the group went

on hiatus so the members could complete South Korea's mandatory

military service.

"The City of Seoul will do its best to make it flexible -

to make (the performance) both safe and enjoyable," said Seoul

mayor Oh Se-hoon on Thursday as he checked safety measures put

in place.

Seoul is staging the event nearly four years after a crowd

crush killed Halloween revellers in the city's Itaewon nightlife

district. Memories of the disaster still linger, amplifying

pressure on South Korean authorities to ensure the safety of

what is expected to be one of its largest-ever public

gatherings.

Seoul police have shut streets and erected fences as well as

metal detectors around the square, which sits to the south of

the Gyeongbokgung Palace. They have also said they will jam

signals of any unauthorised drones.

The Seoul government, BTS' management agency HYBE

and other organisations involved in the event have also deployed

a combined 8,200 personnel to manage the crowds who had already

begun to gather on Friday.

The Seoul government also said it had set up medical

stations and secured 2,551 toilets open to the public including

in nearby buildings.

Organisers of the concert, which will start at 8 p.m. local

time (1100 GMT), gave away 22,000 free tickets, but the area is

open to non-ticket holders who will be able to watch the

performance on Netflix ( NFLX ) via giant screens.

It will also be streamed live on the platform to 190 countries.

Netflix ( NFLX ) and HYBE on Saturday relaxed restrictions on media

coverage of the show, allowing longer audio or video footage of

the ‌performance to be shown but still imposed a ban on

live-streaming by the media.

A 'TRILLIONS OF WON' COMEBACK

BTS' world tour will last into 2027 and is set to be the biggest

global Kpop tour of all time as well as the largest of their

career to date, spanning 34 regions and 82 shows as of this week

according to the tour website.

Analysts are projecting blockbuster revenues for the group's

return to the global stage, with some estimates pointing to

total tour earnings of as much as 2.7 trillion won ($1.81

billion), potentially approaching or overtaking past

top-grossing tours such as Taylor Swift's Eras Tour and

Coldplay's Music of the Spheres World Tour.

Seoul-based analysts also estimated that it could bring in

total ticket revenue of at least 1.5 trillion won and total

attendance of between 5 and 6 million fans across the whole

tour. On Friday, South Korea's finance minister said on X that

the direct economic effect of the Saturday comeback concert

alone was in the "trillions of won".

"The number of shows could reach 100 once dates to be added

next year are included," said Hwang Ji-won, analyst at iM

Securities. "Assuming only 50,000 attendees per show, that comes

to 5 million - and actual attendance could be higher given the

360-degree stage."

A 360-degree, central stage means the audience completely

surrounds the group as they perform. Analysts say such a set

means there are no obstructed views and also increases audience

capacity, boosting sales.

Roughly half the shows are expected to be in North America

and Europe where ticket prices are generally higher, Hwang

added.

Kim Yu-hyuk of IBK Investment & Securities forecast total

tour revenue of 2.7 trillion won and operating profit of 487

billion won including merchandise, expected to be a major

additional revenue driver.

Spending estimates on merchandise range from 100,000 won to

140,000 won per fan, while prices of the new "ARMY Bomb" light

stick that the audience use to cheer BTS at concerts have soared

on secondhand sites.

($1 = 1,492.6000 won)

(Reporting by Joyce Lee; Editing by Brenda Goh, Kate Mayberry

and Muralikumar Anantharaman)