Activists take part in an anti-government demonstration over medicine shortages in Caracas on November 20, 2017

Venezuela launched a program Saturday to hand out medicine to 35,651 patients, blaming US sanctions for a shortage, even as doctors say 95 percent of all drugs are missing.

A government electronic card is required to participate, leading critics to charge the government is favoring its supporters.

Speaking on VTV state television, Health Minister Luis Lopez said the handouts were taking place in 10 of 24 states, and in the rest of the country this coming week.

Francisco Valencia, who leads the health care rights group Codevida, says much more is needed, with an estimated 300,000 patients with chronic illnesses like kidney disease and cancer who are not getting the medications they need.

On Wednesday, patients and their families marched outside the embassies of Canada, the Netherlands, Peru and the United States to press them to urge President Nicolas Maduro to distribute medicine for humanitarian purposes.

The government denies any humanitarian crisis exists, and says US sanctions have complicated medicine imports and distribution.

Lower oil prices on world markets have dramatically reduced the government's main source of hard currency.

Millions of Venezuelans face food and medicine shortages. The South American country has the largest proven crude oil reserves in the world.