Slater has been confined to bed after suffering a relapse

Friday's scheduled opening of One Flew Over the Cuckoo's Nest at the Edinburgh Festival Fringe was cancelled earlier this week after Slater fell ill.

A further three performances have been called off after the 34-year-old developed a secondary infection.

"We are monitoring the situation daily," said producer Nica Burns.

'Totally exhausted'

"He got up from his sick bed yesterday and worked for an hour and a half," Burns said.

"However, by the end of the afternoon he had developed a fever and was totally exhausted."

The True Romance star was diagnosed with a secondary infection, which in some adult cases can lead to pneumonia.

"Christian is therefore confined to bed and on penicillin," Burns said.

Slater's co-stars include Frances Barber and Mackenzie Crook

"He was so keen to get back to work and to not let down the public that he returned to work too early and this relapse is the consequence."

The production, which co-stars Frances Barber and The Office's Mackenzie Crook, was to run at Edinburgh's Assembly Rooms for three weeks before transferring to London's Gielgud Theatre.

It is now being co-directed by Tamara Harvey and playwright Terry Johnson following the departure of original director Guy Masterson, who blamed stress for his decision to leave.

"The company are all rooting for Christian and wishing him a speedy recovery so we can all get this fantastic show back on the road," said Burns.