Labour has accused the government of selling off valuable hospital assets to help plug a hole in NHS finances.
Figures from data body NHS Digital show that the amount of NHS land in England earmarked for sale has more than doubled in the past year.
Analysis commissioned by Labour found 117 sites deemed surplus were still in medical or clinical use.
Ministers said selling land would give vital funds for patient care and free up space for much needed new housing.
The government has set itself a target of selling off enough public sector land to generate £5bn worth of income by 2020.
The NHS is asked to contribute as a major property owner.
NHS property being included for sale includes hospital buildings and some ambulance stations.
But Labour said hospitals were being stripped of their assets and forced into a "fire sale".
Shadow health secretary Jonathan Ashworth said: "This government's refusal to fund the health service has seen standards of care for patients drop and NHS building and upgrade works pushed back.
"The NHS needs an urgent injection of funding to make up for years of Tory underfunding, but the answer is not a blanket sell-off of sites which are currently being used for patient care."
The Department for Health said disposing of surplus land and buildings reduced running costs and it was right to put sites that were no longer needed to economic use.
It said any income generated would be used to improve the quality of the NHS.