The Prime Minister, Dr Manmohan Singh is visiting Kolkata on Thursday to see the ailing Marxist leader and former West Bengal Chief Minister Mr Jyoti Basu. AIR Kolkata correspondent Arijit Chakraborty reports that the CPI(M) General Secretary Mr Prakash Karat and Polit Bureau member Mr Sitaram Yechury are also arriving in the city the same day to see the veteran leader. Mr Jyoti Basu has been admitted in a Private Nursing Home in Kolkata on the 1st of January following attack of pneumonia. He has been put on ventilation after developing respiratory trouble. According to Nursing Home sources his health condition improved slightly on Wednesday afternoon. However, his condition is still critical. A team of doctors constantly monitoring his health. The Trinamool Congress Chief and Railway Minister Ms Mamata Banerjee on Wednesday visited the Nursing Home to inquire about his health.<br/>