Bollywood superstar Amitabh Bachchan on Thursday said he has spoken to ailing Tamil movie icon Rajinikanth and found out from the latter's wife that the actor's heath condition is improving.

"Rajinikanth is improving gradually she informs me, today by sms.. we hope and pray that he recovers as soon as possible.. our prayers, " tweeted Big B after inquiring about the health of the actor with whom he shared screen space earlier.

"All lovers of Rajnikant it has been disturbing to learn of his hospitalization.. I have spoken to him and been in touch with wife, " Bachchan said.

The two actors had in the past shared screen space in films like Hum, Giraftar and Andha Kanoon in the 1980s and 1990s.

Superstar Rajinikanth, who was admitted in hospital again on Sunday last, has been shifted to the ICU Wednesday night for breathing troubles but doctors attending on him said there is no need to panic.

The Tamil actor has been undergoing dialysis and has kidney problems.

The Sri Ramachandra Medical Centre hospital, where he is under treatment, said to improve his breathing pattern he has been shifted to the intensive care unit (ICU) and now he is showing positive response to the treatment.

A Multidisciplinary team are involved, to closely watch his vital parameters to assess benefits from multi prong treatment strategies, the hospital said in a press release.

Doctors say that he is responding well to the treatment.

Rajinikanth has been suffering from recurrent respiratory infection and gastro intestinal ailments and was advised rest.

The 61-year-old star with a god like fan following after the phenomenal success of Robot (Endhiran), which was dubbed in Hindi as well, had recently started working on his new film Rana with Deepika Padukone in Chennai.

He plays three roles in the film on the Mahurat sets of which he fell sick on April 29 and had to be hospitalized first.