Ballance, who has played 23 Tests for England, has yet to feature for the White Rose this season.

A statement from the club said: “Gary is currently managing some heightened feelings of anxiety and stress following a long period of isolation due to the Covid-19 lockdown, his own recent viral illness and other personal factors.

“The post-viral symptoms have affected his physical preparation for this shortened cricket season.

“He is currently unavailable for selection and we are unable to put any timescales on his return to playing at this time.”

The statement added that Ballance has increased his workload in training over the last week, practising in the nets.

“Gary’s health and well-being remains our priority and the club and medical staff will continue to work closely with Gary to support his return to playing as soon as possible,” the statement added.

Ballance, who last played for England in 2017, has been one of the most prolific run-scorers on the county circuit in recent years; only Dom Sibley hit more Division One runs than the 30-year-old last season.