NEW YORK • First, it was a picture in Tibet of a frail-looking Jet Li that floored fans of the action star.

Now, fans of another swashbuckler - Johnny Depp - are in a tizzy after pictures of the Pirates Of The Caribbean actor looking pale and gaunt surfaced online.

Photos of him in St Petersburg, Russia, have sparked intense speculation over the 54-year-old's health.

Depp was in Russia as part of a two-month worldwide tour with his rock band Hollywood Vampires, whose line-up includes Aerosmith guitarist Joe Perry and Alice Cooper.

Fans, playing amateur detectives, think that Depp may be shedding kilos for a new film role.

Others contend that he could be re-shooting scenes for his upcoming movie Richard Says Goodbye.

The plot revolves around a college professor who casts aside his inhibitions after he is hit with a terminal illness.

Other fans believe that Depp could be prepping for another project - a reboot of the 1933 film The Invisible Man. Based on the H.G. Wells science-fiction novel, the plot tracks a scientist who has learnt how to make himself invisible.

But while Depp may look frail now, he is not backing away from a court fight, suing The Sun last week for libel over a story that described him as a wife-beater.

The British tabloid published a story which questioned Harry Potter author J.K. Rowling giving the okay to the casting of "wife-beater Johnny Depp" in a new Fantastic Beasts film.

In December, Rowling had stated that she was "genuinely happy to have Johnny playing a major character" in the spin-off of the Potter film franchise.

Her vote of confidence came amid other media reports of controversy over Depp's casting following his divorce from actress Amber Heard, who had accused him of abuse.