U.S. drugmaker Pfizer Inc said on Monday it would maintain humanitarian supply of medicines to Russia and would donate all profits from its unit in the country to causes that provide direct support to the people of Ukraine.

The company said it would no longer start new clinical trials in Russia, and stop recruiting new patients in ongoing studies in the country.

The Russian invasion has left drugmakers scrambling to find ways for patients enrolled in clinical trials in Ukraine to receive their medicines as millions seek shelter from bombardment and flee to neighboring countries.

Russia has described its actions as a "special operation".

Pfizer said a voluntary pause in the flow of medicines to Russia would be "in direct violation of our foundational principle of putting patients first".

The drugmaker, which does not own or operate any manufacturing sites in Russia, said it would stop all planned investments with local suppliers intended to build manufacturing capacity in the country.

Global companies like McDonald's, Nestle and video gamemaker Sony have decided to step back from Russia as pressure mounts from consumers in the West to take a stand against the invasion.

(Reporting by Manojna Maddipatla in Bengaluru; Editing by Anil D'Silva)