Prime Minister will not attend the Republic Day parade to be held on Monday. It is learnt that his staff is planning to keep his participation at public gatherings minimal. He is expected to attend only some of the important functions like 'Beating the Retreat'.

Earlier, doctors examining Prime Minister Manmohan Singh, did not rule out possibility of bypass surgery.They were also mulling other options even after he was discharged from the All India Institute of Medical Sciences on Thursday after undergoing angiography.

"There are three options which are on the cards - angioplasty, bypass and controlling the problem with medicines. We have not ruled out any of these. The whole planning process among the doctors is evolving and we should not say anything specific as of now. It will take a few more days to decide on medical intervention," Dr K Srinath Reddy, chairman of the PM's medical panel told The Indian Express.

Sources at the premier institute, however, revealed that he is likely to undergo bypass surgery, which would require him to rest for at least one month though the other options were also discussed with the PM's family members on Wednesday.

The 76-year-old had undergone coronary artery bypass surgery in the UK several years back. He also underwent angioplasty in the Escorts Heart Institute about five years back.