"The PM spoke to the family of former union minister Jaswant Singh this morning. He prays for Singh's speedy recovery," the PMO tweeted.
The former Bharatiya Janata Party (BJP) leader was admitted to the Intensive Care Unit (ICU) of the Army Research and Referral hospital here early Friday.
Singh is under the observation of neurosurgeons and critical care specialists, a doctor at the hospital requesting anonymity said.
Meanwhile, a staff member at senior BJP leader L.K. Advani's residence here said the leader was present at the hospital and added that, as per information, Singh had been operated upon and that the operation "went well".
A former minister of defence and external affairs, Singh parted ways with the BJP after long years of association just before the 2014 general elections. He contested the Lok Sabha polls from Rajasthan as an independent candidate and lost.