Actor Shammi Kapoor, who is undergoing treatment in a Mumbai hospital, has developed renal problems, sources said.

His condition remains 'critical but stable', the sources at the Breach Candy Hospital.

"He is under observation for urine output and creatinine level," the sources said.

Kapoor, who had been suffering from bronchitis, was admitted to the hospital after he developed serious lung congestion.

He continues to be in the ICU, they added.

Brother of legendary actor-producer Raj Kapoor, the veteran actor had shot to fame with films like Junglee, Brahmachari, Teesri Manzil and Kashmir Ki Kali.