People based in the area complained about intrusive lights, with video circulating on social media showing the X sign emitting a blinding white pulsing light, particularly affecting a high-rise building on the other side of the street.

The company's new sign is part of owner Elon Musk's rebrand of Twitter, which he claims will involve the creation of an "everything app".

But the Californian city's department of building inspection said the structure may violate permitting rules.

An inspector said in a written statement that officials were denied access to the building's roof twice by Twitter representatives to inspect the logo. The inspector noted one staff member said the sign was temporary.

The sign remained on top of the building on Sunday.

The X appeared after San Francisco police stopped workers from removing the brand's decade-old bird and logo from the side of the building earlier this week, saying they had not taped off the footpath to keep pedestrians safe if anything fell.

Any replacement letters or symbols would require a permit to ensure "consistency with the historic nature of the building" and to make sure additions are safely attached to the sign, Patrick Hannan, spokesperson for the department of building inspection, said earlier this week.

Erecting a sign on top of a building also requires a permit, Mr Hannan said.

"Planning review and approval is also necessary for the installation of this sign. The city is opening a complaint and initiating an investigation," he said.

The department opened a separate investigation in December into a complaint alleging Mr Musk had built bedrooms in the San Francisco headquarters for workers.

The rebranding is the latest major change since he bought Twitter in October last year for $44 billion (£34.3 billion).

Click to subscribe to the Sky News Daily wherever you get your podcasts

The changes include the apps "verified" blue tick status being monetised in April and a temporary limit at the start of July on the number of posts users were allowed to read.

The long-standing blue logo, known as Larry the Bird, has been Twitter's emblem since its creation in 2006, with the current design in use since 2012.

In April, Musk briefly replaced the logo with a small picture of a Shibu Inu dog, famously known as the Doge meme, in an apparent nod to the cryptocurrency Dogecoin.

Musk, who is also CEO of Tesla, had already renamed Twitter's corporate name to X Corp. He also named one of his children X.

Read more:
Why rebranding Twitter will be an enormous challenge
Twitter user gives up @X username to platform's official account after 16 years

The changes at Twitter prompted Facebook owner Meta to launch Threads, its own text-based conversation app, earlier this month.

Meta chief executive Mark Zuckerberg said more than 30 million people had signed up to use his rival messaging app in the first 24 hours.

Twitter threatened to sue the company over what it alleged were stolen trade secrets.

The investigation into the logo comes as the company reinstated Kanye West's account after eight months' suspension.