Status Quo star Rick Parfitt is to undergo a battery of medical tests in his native U.K. to determine the nature of a mystery illness which led to the cancellation of a number of tour dates.

The 65-year-old singer/guitarist was hospitalised in Pula, Croatia after falling ill onboard the group's tour bus on Friday (01Aug14), and his wife has revealed he was due to fly back to the U.K. on a private jet on Monday night (04Aug14) to continue his medical care.

Lyndsay Parfitt, who lives in Spain with her husband, explains the hospital in Croatia is "very basic" and she hopes doctors in Britain will be able to find out what is wrong with the rocker.

She tells Britain's Daily Mirror newspaper, "He sounds very flat and not himself at all. The staff at the hospital have been wonderful. But it is very basic and we want to get some proper tests done to find out what the problem is."

The musician's son, Rick Parfitt, Jr., has also reached out to fans to assure them his dad is doing well, writing in a series of posts on, "Thank you for all the kind well wishes. Have spoken to dad today and all signs are good that he will be back rocking soon... Have been reassured that all is ok."