Serum Institute of India CEO Adar Poonawalla on Friday urged US President Joe Biden to lift the embargo on export of raw materials used in the production of the Covishield coronavirus vaccine in India.

Mr Poonawalla took to Twitter to remind the US President that the world had to "truly unite" to beat the pandemic, and that blocking access to raw materials would affect production of both the Covishield, which SII supplies to several countries and Novovax which will be hitting the market soon.

"Respected POTUS, if we are to truly unite in beating this virus, on behalf of the vaccine industry outside the US, I humbly request you to lift the embargo of raw material exports… so vaccine production can ramp up," he tweeted.

The Serum Institute is the world's largest vaccine manufacturer by volume, and is playing a major role providing doses to protect a large portion of the global population against the COVID-19 pandemic.

It is also the main supplier of Covid vaccines for the Indian government. Hyderabad-based Bharat Biotech being the other company which  is supplying Covaxin but in much smaller quantities.

The US' ban on export of raw materials came into effect in February.

The Biden administration invoked the Defence Production Act – which gives "powers to control distribution of products" – for "the short term", according to The Washington Post, to ensure US pharma giant Pfizer had access to resources needed to scale up production of its vaccine.

The export ban was imposed after US pharma major Pfizer said it was having difficulties meeting delivery deadlines for the roll out of its vaccines.

Mr Poonawalla had then said, "This is  one thing that would need some discussion with the Biden administration… to explain to them there's enough to go around."

In early March Mr Poonawalla had also said in his comments to a World Bank panel, "If we're talking about building capacity all over the world, the sharing of these critical raw materials is going to become a critical limiting factor – nobody has been able to address this so far," he had said.

The Serum Institute currently produces around 65 million doses per month, which have been "prioritised" for India, despite concerns from other nations.

Mr Poonawalla has said he wants this to increase to around 100 million per month, but that will require significant investment and time, and, now, an uninterrupted supply of raw materials.