The central government has asked the Serum Institute of India and Bharat Biotech to lower the price of COVID vaccines, Covishield and Covaxin which were recently increased to a higher unexpected price, as India gears up to vaccinate all aged above 18 from May 1, official sources said on Monday.

The Pune-based Serum Institute of India (SII), the world's largest vaccine maker in terms of volume, has announced a price of Rs 400 per dose for its COVID-19 vaccine, 'Covishield', for state governments and Rs 600 per dose for private hospitals.

The Hyderabad-based Bharat Biotech has fixed the price of its COVID-19 vaccine, Covaxin, at Rs 600 per dose for state governments and at Rs 1,200 per dose for private hospitals.

Both vaccines are available to the central government at a rate of Rs 150 per dose.

This comes after many state chief ministers, including Mamata Banerjee, Arvind Kejriwal and several others had questioned the non-uniformity in COVID-19 vaccine pricing for the state and private hospitals.

India has announceda 'Liberalised and Accelerated Phase 3 Strategy of its COVID-19 vaccination drive by allowing its large 18-plus population to get inoculated from May 1.

As per the new policy, vaccine manufacturers are empowered to release up to 50 per cent of their supply to state governments and in the open market at a pre-declared price.

Terming the new anti-COVID vaccine policy "discriminatory and insensitive", the Congress on Sunday had accused the government of allowing vaccine makers to profiteer to the tune of Rs 1.11 lakh crore.

The Serum Institute of India (SII) has, however, defended pricing Covishield vaccine at 1.5 times the initial rate, saying the earlier price was based on advance funding and now it has to invest in scaling up and expanding capacity to produce more shots.

In a statement on Saturday, the Serum Institute clarified that there was an "inaccurate comparison" done between the global prices of the vaccine with India.

"Covishield is the most affordable COVID-19 vaccine available in the market today," SII said.