Image copyright AFP/Getty Image caption Pierre Delecto, otherwise known as Mitt Romney, is a Republican senator for Utah

US Republican Senator Mitt Romney has revealed he uses a secret Twitter account under the name Pierre Delecto.

In an interview with The Atlantic magazine on Sunday, the former presidential candidate admitted he had a "lurker" Twitter handle to follow the US political conversation anonymously.

While he did not reveal its name, US news site Slate posted an article speculating it could be Pierre Delecto, @qaws9876.

Asked to confirm by a journalist, Mr Romney said, "C'est moi" ("It's me").

The Utah senator and former governor of Massachusetts is an outspoken critic of President Donald Trump, a fellow Republican. It is unknown why he chose the account name, Pierre Delecto.

How was his secret exposed?

News first broke of the secret Twitter account in a profile piece written by McKay Coppins in The Atlantic.

Coppins asked the senator about President Trump's prolific tweeting - including attacks on Mr Romney himself - and prompted the revelation that he "uses a secret Twitter account - 'What do they call me, a lurker?' - to keep tabs on the political conversation".

Media playback is unsupported on your device Media caption Trump reacts to Romney's attack: "I wish Mitt could be more of a team player"

The senator did not give away the name, but listed some of the roughly 700 accounts he follows - including journalists, athletes and comedians.

Mr Trump was not among them. Mr Romney said in the interview the president "tweets so much", comparing him to his niece on Instagram. "I love her, but it's like, Ah, it's too much."

Who is Pierre Delecto?

All this was not enough for Slate journalist Ashley Feinberg, who launched an investigation into what possible account the senator could be using.

Scouring Mr Romney's grandchildren's Twitter accounts revealed Twitter user @qaws9876, known as Pierre Delecto. The account has since been made private.

It first opened on the social media site in July 2011, one month after Mr Romney announced plans to run for the presidency. Pierre Delecto follows a number of Mr Romney's family members and former aides.

The account has only tweeted a handful of times, all in reply to other tweets.

Image copyright @qaws9876

Coppins, who wrote the Atlantic piece, then called Mr Romney to see if the speculation was accurate.

Asked if he was indeed Pierre Delecto, Mr Romney gave his brief reply in French. The senator had learnt the language while doing missionary work in France as a young man.

Who is Mitt Romney?

Mr Romney ran unsuccessfully for the presidency in 2012, losing to incumbent Barack Obama.

Since January 2019, he has served as the junior US senator from Utah.

He has publicly questioned Donald Trump's fitness for office, writing in the Washington Post that the president had not "risen to the mantle" of his office.

Mr Trump has attacked the senator several times, most recently calling for his impeachment on Twitter.

Who else has used fake names?

Mr Romney is not the only US politician to use a pseudonym:

Former FBI Director James Comey - who was sacked by President Trump in May 2017 - tweeted under the name of American theologian Reinhold Niebuhr. Reporter Ashley Feinberg again was behind speculation it was him before he confirmed his use of the account in October 2017