The condition of former West Bengal chief minister and veteran Marxist leader Jyoti Basu turned 'very critical' with deterioration in his cardiac and renal functioning. <br/><br/>Executive Director of AMRI Hospital D N Agarwal, told reporters that Mr. Basu has been put on dialysis and his oxygen requirement has increased. <br/><br/>The 95-year-old leader was admitted to the hospital on January one. He was diagnosed with pneumonia.