Rihanna has sparked health fears after pulling out of a UK trip.

The 24-year-old singer had been due to fly into London yesterday to film a TV special at the beginning of a 10-week stay but the star has suddenly canceled all her British commitments, prompting speculation she has been partying too hard.

"She canceled her trip and all work commitments in the UK at the very last minute, which is very unlike her. She has been hitting it hard for months. She smokes, drinks and parties hard on top of work commitments," a source told The Sun.

The "What's My Name" hitmaker's management cited "sickness" for her axing of the TV show. It is not yet clear whether her performances at the Hackney Weekend and Wireless festivals in London will be affected.

Rihanna herself hasn't commented on her canceled trip, but posted a cryptic message on Twitter yesterday. "Keep your eyes on the finish line and not on the turmoil around you #thinkahead (sic)" it read.

The "We Found Love" star was rushed to hospital suffering with "exhaustion and dehydration" last month. She Tweeted a picture of herself attached to a drip in a hospital after reportedly spending the night partying at the Met Gala in New York. However, after a brief stay in the undisclosed medical center, she was discharged and allowed to fly back to her home in Los Angeles.

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