Pop star Miley Cyrus hit back at claims she had taken a drug overdose after a bout of ill health threatened to disrupt the UK leg of her Bangerz tour.

The Wrecking Ball singer used a brief, typically energetic and expletive-laden press conference to boast about her fine physical health after a sinus infection - compounded by an unexplained bereavement - consigned the singer, actress and dancer to her sick bed.

The former Disney star was forced to postpone her US tour last month but has begun the European leg and will resume performances in America on August 1.

But she said she was "the poster child for good health" as she prepared to embark on the UK stint of her arena tour - and promised to "f*** this place up".

The chart topper, urged by a member of her entourage not to answer the journalist's "poor" question about what had happened to trigger the illness, dryly added: "But when people are lying on the internet saying you've had an overdose, that makes you feel better."

She said: "I'm feeling good, I'm alive, so that's f*****g awesome. Look at me, I'm the poster child for good health.

"I've been laying down for three weeks. I'm gonna go off - I'm like a star waiting to explode.

"I didn't have a drug overdose. I took some s****y antibiotic my doctor gave me and I had an allergic reaction.

"I already had a death in my family so my immune system was already low."

Cyrus, who spent her short time in the UK sightseeing ahead of last night's gig at London's O2 Arena, set the tone for the heavily choreographed show from the moment she arrived on stage via a long, pink slide built to resemble her tongue, protruding from an image of her face which was the backdrop to the show.

Wearing a silver one-piece - her first costume of the night, replete with a stick-on pair of lips - Cyrus referenced her recent ill-health when she yelled: "Hello, mother f*****s! I'm not going down without a motherf*****g fight!"

She launched into tour opener SMS (Bangerz) accompanied by a pantomime horse, a midget and a troupe of dancers.

Her on-stage antics and risque costumes have divided audiences, a reputation compounded by her provocative "twerking" dance at last year's VMAs and the show delivered, as promised, a certain measure of the unexpected, if the reaction from some parents was anything to go by.

While many in the young crowd mouthed the words to Cyrus' lyrics, older audience members were less impressed with the show - which included Cyrus slapping herself in an intimate area, simulating foreplay on a bed with a dancer, and repeatedly showering fans in the front few rows with gargled water.

One father, attending with his 15-year-old son, said of the content: "It would be different if it was a good show. But it's not even a good show."

Another added: "She's lost the plot."

The set list included a bizarre interlude featuring a black and white film of a near-naked Cyrus pulling faces set to Mercury prize winning British band Alt-J's Fitzpleasure, before returning to a satellite stage and taking a selfie.

When the music resumed, it included cover versions of Arctic Monkeys' Why'd You Only Call Me When You're High and Bob Dylan's When You Go.

She also offered renditions of Summertime Sadness by Lana Del Ray and covered Jolene, a song made popular by her godmother, Dolly Parton.

Cyrus's finale featured her soaring over the stage while strapped onto "the biggest wiener in London" - an inflatable hot dog.

Her first encore included her biggest hits - UK number ones We Can't Stop and Wrecking Ball - and the show finally closed with a pyrotechnic display and Party in the USA, with Cyrus altering the lyrics to reflect her location for the evening while wearing a Union flag one-piece.

The tour continues in Leeds on Saturday and Glasgow, Manchester and Birmingham next Monday, Wednesday and Friday respectively.