The boards have to be put up at the gate of all hospitals, the city government said in an order.
Delhi Chief Minister Arvind Kejriwal has been appealing to people, who have recovered from the disease, to come forward and donate plasma to COVID-19 patients.
He had also said there are not many donors and had appealed to hospitals to encourage their recovered patients to donate.
"With a view to encourage persons who have recovered from COVID-19 to donate their plasma to help other COVID-19 positive patients, it is decided to display flex boards of 12X10 ft at the entry gate of all hospitals in Delhi," the order said.
It said that accordingly, "all MS/MDs/Directors of all Hospitals of Government of NCT of Delhi and private Hospitals in Delhi are directed to install display board at their entry gate to display the information as per format enclosed".
The flex board will display the helpline number '1031' through which recovered patients can register for donating plasma.
Last week, Kejriwal inaugurated the country's first plasma bank at the state-run Institute of Liver and Biliary Sciences (ILBS) in Vasant Kunj to facilitate plasma therapy treatment for coronavirus patients. SLB ANB ANB