Sir Tom Jones has announced his plans to delay a planned U.S. tour until 2018 due to health concerns.

The 77-year-old icon was scheduled to begin the month-long tour in Bethlehem, Pa., on Wednesday. But on Saturday, he posted a statement on social media about the postponement, while just a few days earlier he had shared that Into the Ark would be joining him on the tour.

Jones was "following medical advice," by delating the tour, the statement read, but no additional details were given on his condition.

Tour dates are being rescheduled for May and June 2018, at which time current tickets will be honored. Alternatively, ticket holders can seek a refund at their point of purchase.

"Tom sends his sincere apologies to his fans and looks forward to seeing them all again in 2018," the message read. Many loyal fans began posting messages to him on Facebook and Twitter, wishing him well and praying for his speedy recovery.

Jones completed a European tour last month. His career as a musician, actor and television host has spanned six decades. His music career debuted in 1965 with Along Came Jones, which launched the one of his best-known hits, "It's Not Unusual." In 2015, he put out Long Lost Suitcase. The album accompanied his memoir, Over the Top and Back. This year, he appeared as a coach on the music competition show The Voice.

Jones has reportedly been "struggling emotionally" since the death of his wife, Linda, last year. The two had been married for 57 years.

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