Indian Prime Minister Manmohan Singh underwent medical tests Tuesday and Wednesday for heart-related problems at a government-run hospital in New Delhi, the Press Trust of India reported.
The tests included an angiogram that revealed some arterial blockages in his heart, and doctors were debating the next course of action, PTI said.
Singh, 76, was advised to take the tests after he complained of chest pain, the report said, quoting unnamed sources.
Deepak Sandhu, Singh's spokeswoman, told AFP he had visited the All India Institute of Medical Sciences Tuesday for an "overall medical checkup."
She did not confirm the nature of the procedures but added some "diagnostic tests" were scheduled for Wednesday.
Singh has largely been in good health since he was sworn in as prime minister in May 2004 but he recently underwent surgery for a "benign enlargement" of the prostate gland and has also had cataract treatment.
PTI said doctors had kept an operation theatre ready for surgery as a precautionary measure.
India is due to hold general elections before May.